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For servo special reducer, no matter what form, usually involves the performance indicators discussed below. However, due to commercial needs, manufacturers generally do not have clear definitions of the parameters on their samples, which makes it difficult to compare products. Therefore, before discussing the indicators, we first define two important concepts that describe the working condition of the gearbox
1， Duty cycle (ED)
Duty ratio refers to the percentage of the actual operation time of the reducer in a complete working cycle. This is a parameter to determine whether the working mode is S1 (continuous work) or intermittent work (S5). It is calculated as follows: Duty cycle Ed =(acceleration time + working time + deceleration time)/(acceleration time + working time + deceleration time + pause time)
2， S1，S5
The concept of working mode standard is derived from motor applications and is established by the International Electrotechnical Commission (IEC). Later extended to all to the motor drive as the main driving source of the transmission parts of the working mode.
S1 -- Continuous operation mode, running under constant load for a period of time to achieve motor heat balance. "Heat balance" refers to the temperature rises to a certain value after no longer rising, through effective heat dissipation and the surrounding environment to achieve temperature balance.
But because the temperature limit of different products is different, it is usually the part with the weakest thermal stability value in various parts of the product, such as the motor generally refers to the coil, and the gear box generally refers to the grease, because the temperature is too high may damage the stability of the oil film. Fig. B-18 shows the temperature rise curve of a typical motor.
Over time, we're in thermal equilibrium
In the application of gearbox, manufacturers will often give specific values to define the working mode according to their experimental data.
S1 operation mode (continuous operation mode) means that the gearbox operates uninterrupted for more than 15 (20) minutes, or the duty cycle is greater than 60%, and the temperature of the gearbox shall not exceed 90 (70) ° C. The data in () are different values provided by some manufacturers. ---- Industry standards are a mess!
S5 working mode (intermittent working mode) means that the duty cycle is less than 60% and the start/stop frequency needs to be assessed. In other words, the start/stop frequency should not exceed 1000 times within an hour. Otherwise, the impact coefficient FS should be multiplied when calculating the maximum torque.
It is worth noting that: in the actual selection, we often omit the working mode, and the rated torque index separated from the working mode can not be used as the selection index, which is often ignored in the actual selection, and then lead to the accident damage problem in the use of the reducer.
