Key points for selecting universal reducers
The selection of universal reducers includes steps such as proposing original conditions, selecting types, and determining specifications.
In contrast, the type selection is relatively simple, and accurately providing the working conditions of the reducer and mastering the design, manufacturing, and usage characteristics of the reducer are the key to correctly and reasonably selecting specifications for universal reducers.
The specification selection shall meet the conditions of strength, Thermal equilibrium, and radial load on the shaft extension part.
1. Select specifications based on mechanical power or torque (strength verification)
The biggest difference between the design and selection methods of universal reducers and specialized reducers is that the former is applicable to various industries, but the reducer can only be designed according to a specific operating condition. Therefore, when selecting, users need to consider different correction factors according to their own requirements. Factories should label the motor power (not the rated power of the reducer) according to the actual selection; The latter is designed according to the specific conditions of the user, and the coefficients to be considered are generally taken into account during design. When selecting, it is relatively simple to ensure that the power used is less than or equal to the rated power of the reducer.
The rated power of general reducer is generally calculated and determined based on the use (working condition) coefficient KA=1 (the motor or turbine is the prime mover, the working load is stable, the working time is 3~10h every day, the number of starts per hour is ≤ 5, and the allowable starting torque is twice the working torque), the contact strength Factor of safety SH ≈ 1, the failure probability of a single pair of gears ≈ 1%, and other conditions.
The rated power of the selected reducer should meet
PC=P2KAKSKR ≤ PN
In the formula, PC - calculated power (KW);
PN - Rated power of the reducer (KW);
P2- Working machine power (KW);
KA - service coefficient, considering the impact of service conditions;
KS - Starting coefficient, considering the influence of starting times;
KR - Reliability coefficient, considering different reliability requirements.
At present, the usage coefficients used by countries around the world are basically the same. Although many samples do not reflect the two coefficients of KSKR, due to knowing oneself (having clear requirements for its own operating conditions) and knowing others (having clear performance characteristics of reducers), foreign selection generally leaves a large margin, which is equivalent to considering the influence of KRKS.
Due to different usage scenarios, varying degrees of importance, varying degrees of damage to personal safety and production, and varying degrees of difficulty in maintenance, the requirements for the reliability of reducers are also different. The coefficient KR is the actual required reliability to modify the reliability of the original design. It complies with the provisions of ISO6336, GB3480, and AGMA2001-B88 (American Gear Manufacturers Association Standard) for gear strength calculation methods. At present, some domestic users do not have specific requirements for the reliability of reducers, and can follow the design regulations of general specialized reducers
