The entry-level selection method for planetary gearboxes
The impact of each link on the reducer:

Gears: The machining accuracy, tooth profile, heat treatment process (hardness), material, etc. of gears directly affect the accuracy and service life of the reducer.

Bearings: The industry generally adopts bearings imported from Japan or produced in Taiwan.

Lubricating grease: affects transmission efficiency, thermal conductivity, and gear life.

Planetary carrier: The integrated structure has higher rigidity, stronger reliability, and higher concentricity, but it is more expensive and requires higher processing equipment. The split structure is simple and cost-effective, making it easier for factories to standardize production.

Sun gear: Same as above.

Ring gear: Split type ring gears have poor reliability, short lifespan, and rapid accuracy degradation.

Oil seal: To prevent motor failure caused by oil leakage.

Shell: electroplated, painted or baked to improve the tolerance of the gearbox to the operating environment.

1、 Selection calculation

Speed ratio=actual required torque/rated torque of motor

Speed ratio=rated motor speed/final output speed

Similarly, output speed=motor speed/speed ratio (negatively correlated)

Output torque=motor torque * speed ratio (positively correlated)

The selection of reducer should meet the following requirements simultaneously:

Output speed ≥ motor speed/speed ratio

Output torque ≤ gearbox capacity (including comparison of peak torque)

[Note: The above calculation formula is only applicable for rough calculation. In actual gearbox selection, many factors need to be considered, such as gearbox usage coefficient, transmission efficiency, environmental temperature, etc. Among them, the most important factor is transmission efficiency. Currently, the transmission efficiency of planetary gearboxes can generally reach over 95% (single-stage deceleration, multi-stage deceleration transmission efficiency decreases in multiple directions). Therefore, in actual selection, a margin of about 10% to 20% should be left.]

2、 The four elements of gearbox selection:

Appearance: shaft output, hole output, or surface output; Linear or angular type.

Dimensions: input end (connected to motor) flange surface, aperture. Output end (connecting device) flange surface and aperture.

Speed ratio: Calculate the required torque by multiplying the actual torque of the motor by the speed ratio.

Accuracy: The accuracy is reflected by the gear clearance that occurs in the forward and reverse rotation of the reducer gear, measured in arc minutes, where 1 arc minute equals 1/60 degrees.

3、 Related knowledge

1. Because the gearbox needs to withstand greater torque, the output shaft of the gearbox is generally thicker than that of the motor, and the body may also be larger.

2. The transmission efficiency of multi-stage deceleration is lower than that of single-stage, and the backlash is also enlarged, which means the accuracy is relatively poorer.

3. The actual output torque of the reducer will be greater than the designed capacity (the reducer itself has a designed capacity), so in practical applications, some customers can use it without leaving any margin when selecting.

4. In terms of accuracy selection, customers can determine the allowable error value through torque amplification calculation, that is, by calculating the circumference, the angle difference generated by each rotation of the reducer is converted into line length. This value is not greater than the allowable error value, indicating that the accuracy is qualified.

5. Different purposes can be achieved by utilizing the different characteristics of the gearbox. For example, slowing down, increasing torque (to a multiple of the corresponding speed ratio), and reducing moment of inertia (to the square of the speed ratio).

6. The helical gear reducer has a larger meshing surface, good precision, and can withstand greater torque, running smoothly and quietly; Straight teeth are prone to vibration, have slightly lower accuracy, and produce excessive noise.