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When choose the grid couplings, according to the basic information, work out the torque, and select the model specification preliminary. Then found the specification from standards, which corresponding to the maximum aperture, the maximum radial dimension (Rotary space) and the allowable speed meeting working conditions of couplings  to confirm the model specifications of grid couplings.

 

Choosing grid couplings should be based on the following procedures.
 

1.1 Choose the basic information 

Designation of driver, quantity, input power, service speed, designation of work machine, type of load, working environment, nature of work, starting frequently or not, whether positive & negative, input and output shaft diameter and length.

Basic information can be seen in table 1.

 

1.2 Calculation

The main parameter of the coupling is the nominal torque (Tn). Various torque should accord with the following relationship when is chosen:

T＜Tc≤Tn≤［T］＜［Tmax］＜Tmax

In the formula:

T ─ Theoretical torque, N·m

Tc ─ Calculated torque, N·m

Tn ─ Nominal torque, N·m

［T］─ Allowable torque, N·m

［Tmax］─allowable maximum torque, N·m

Tmax─ maximum torque，N·m

 

1.2.1 Couplings theories torque calculation                                                                                                                                            

T=9550Pw/n  

In the formula:

 Pw ─ driving power, kW

 n ─ working speed, r/min; 

 

1.2.2 Calculating calculated torque of the coupling

Calculation formula Tc = T·Kw·K·z

Kw ─ Coefficient of engine (Table 1)

K ─ working condition coefficient (Table 1)

Kz ─ start coefficient (Table 1)
 

1.2.3 When the following situations happen, it should be worked out and selected by using the following methods:

①High peak loads

②Brake (brake wheel or brake disc is part of the coupling)

③High frequency axial channeling move

 

Peak load

When system has repetitive peak load such as high motor power, impulse load, frequent launching and braking, intermittent operation, nominal torque should be worked out by using following formula. 

 

a. No reverse peak load

Selection torque (N·m) = system peak torque

or selection torque (N·m) = System peak power (Kw)×9550/rotate speed (rpm)

 

b. Reverse peak load

Selection torque (N·m) = 1.5×system peak torque

or selection torque (N·m) = 1.5×system peak power (Kw)×9550/rotate speed(rpm)

 

c. Occasional peak load (no reverse)

During life expectancy of the coupling, if the system peak load’s frequency of occurrence is less than 1000 times, use the following formula:

Selection torque (N·m) = 0.5×system peak torque

or selection torque(N·m) = 0.5×system peak power(Kw) ×9550/rotate speed(rpm)

For reverse situation, select the step b.

 

Brake

If the brake torque exceeds the motor torque, work out braking power according to the following formula:   

Selection torque (N·m) = brake torque × application factor 
 

High frequency axial floating

If the axial floating is higher than 5 times per hour, the working condition coefficient should be increased by 0.25.

Selection torque (N·m) = power (Kw)×9550×(application factor+0.25) /rotate speed(rpm)

 

1.3 Select model specifications of coupling preliminary.

1.4 Selection verification

1.5 Determining the model specifications of coupling. 

1.6 Product marking

 

Selection example.
 

2.1 General information

Motor rated power 3KW

Output revolving speed 686rpm

Input shaft diameter d1 48 mm

Output shaft diameter d2 60mm

Distance between input end and output end 108mm

 

Working environment:

Working temperature: -30 ℃ -120 ℃

Load Properties: Medium Impact

Surrounding environment: dust, etc

Job nature: continuous

 

2.2 Selection calculation 

According to the general information, SD standard Steel flex-grid coupling is chosen in this project.

Theoretical toque calculation

T=9550Pw/n=9550*3/686=41.8（ Nm）

Calculated torque

Computational formula  Tc=T·Kw·K·Kz

In this formula: Kw = 1

K = 2

Kz = 1

Tc = 41.8*1*2*1=83.6（ Nm）

 

2.3 Primary selected model specifications of coupling 

The nominal torque of 1030T 10: 150Nm  

Meet the torque requirement: primary selection of 1030T10

 

2.4 Verification

2.4.1 Bore diameter

The max bore diameter of 1030T10: 35mm

If bore diameter dose not meet the requirements, model specifications need to be adjust.

1070T10 Max bore diameter of 1070T10: 64mm.  Meet the requirements of bore diameter.

After adjustment, the coupling model specification is 1070T 2.4.1 Aperture

 

2.4.2 Rotary space (compared with site conditions)

There is no restriction on the max diameter of the couplings. This shall be regarded as meet the requirements

1070T10: Meet the requirements of rotary space.

 

2.4.3 Allowable speed

Allowable speed of 1070T10: 4125rpm

The actual output speed of coupling is 686rpm

1070T10 meet the allowable rotate speed

 

2.5 Selected model specifications of coupling 

Because the distance between input and output end is 108mm, determination of the coupling model specifications as follow. 

Two sets of 1070T10 48*L/60*L C=108 with connecting shaft

 

2.6 Marking Example

1070T10 flexible grid coupling

Input end: J1 type shaft hole, Type A keyway, d=48mm, L=76mm 

Output end: J1 type shaft hole, Type B keyway, d=60mm, L=76mm 

1070 T10 coupling J1 A 48*76/ J1 A 60*76, separation distance C=108

For more information concerning grid couplings, please refer to the following articles:
Structure and Application of Grid Couplings
Structural Types of Grid Couplings
Rapid Cooling Setup and Connection of Grid Couplings
Carrying and Storage of Grid Couplings
Installation and Adjustment of Grid Couplings
Usage and Maintenance of Grid Couplings
Basic Info for Model Selection of Grid Couplings