How to choose electromagnetic clutch and electromagnetic brake
Electromagnetic clutches and electromagnetic brakes have been widely used in machine tools, instrumentation, packaging, textiles, papermaking, printing, office, woodworking, and tobacco machinery, and have become important implementing elements for realizing mechanical automation. It has a compact structure and simple operation. Easy to realize the advantages of long-distance centralized manipulation and automatic control. In recent years, with the rapid development of the level of mechanical automation in China, the structure, performance and reliability of electromagnetic clutches and electromagnetic brakes have become increasingly perfect, and the product varieties have become more complete. In order to improve the quality of the main engine product, reduce costs, and improve product reliability, the electromagnetic clutch and brake should be selected correctly and reasonably.
1. Type selection The type selection of electromagnetic clutches and brakes should be selected according to the requirements of the host product's use environment, lubrication conditions, action response time, and the characteristics of the electromagnetic clutch and electromagnetic brake products.
1. Toothpick clutch products are small in size, large in transmission torque, and can be used in both dry and wet conditions. They can be installed vertically and have a long life. They are suitable for use in stationary or low-speed combinations.
2. Wet multi-plate electromagnetic clutch (brake)
The product has little wear during use, does not need adjustment, impact resistance, vibration, semi-permanent life, horizontal installation, slightly idling torque, and is used under lubricated conditions or in gear boxes.
3. Dry multi-plate electromagnetic clutch (brake)
The product has a small radial size, fast action time, adjustment after wear, good heat dissipation, and low no-load torque. It is suitable for use in situations without lubrication and requiring fast action time.
4.Dry type single disc electromagnetic clutch (brake)
The product has fast action response, no no-load torque, convenient installation and use, and can be used vertically. It is suitable for use under non-lubricated conditions and frequent action. The combination of clutch and brake is better.
5. Power-loss brake products are designed to work without power, save energy, and move quickly. They are suitable for safe holding and fast braking applications.
Selection and calculation of moment capacity
Friction torque includes dynamic distance and static torque, which should be selected according to the use of the load. The calculation of the torque of the prime mover alone is very dangerous and should be considered comprehensively.
1． Torque calculation formula (clutch or brake shaft)
(a) Original machine torque T
(B) Ta is required for acceleration of the load GPS2
2． Determined according to the nature of the load
(A) The load moment and DG2 are small when combined, and the load moment increases after combined.
(B) The combination is to overcome the full load.
In case (a), the clutch dynamic torque TD that must be required is:
| Td = GD.Dn / 375tac + Te1 ------ (Kg.m) |
:连接时的负载扭距---Kg.m Where T e1 : load torque when connected --- Kg.m
1/2 以下时，离合器容量要根据静磨擦力矩s选定。 When Ta is less than 1/2 of the maximum load torque T e2 after coupling, the clutch capacity is selected based on the static friction torque s.
>T E2 .f------Kg.m T S > T E2 .f ------ Kg.m
f: safety factor, see table on the right
In the case of shock load, etc., a sufficient safety factor should be selected. In case (b), the capacity is selected based on the clutch power distance TD.
T d> = (GD.Dn / 375tac + Te1) .f --- (Kg.M)
In this case, regardless of the speed of the shaft, the actual combined time tac is safer than 0.5 to 1 second.
f: safety factor table
| Kind of prime mover |
Load of machinery type
| Motor |
| 4-6 cylinder |
| 4-6 cylinder |
| The load does not change and the inertia is small. |
Blower, fan, office machinery
| 1.5 || 1.7 || 2.1 |
| Small inertia, low frequency working small machine tools, textile machines, small woodworking machines, etc. || 1.7 || 2.0 || 2.4 |
| Large load inertia, medium press crane, power wire machine, etc. || 2.4 || 2.8 || 3.4 |
| Low frequency working large machine tools, small presses, textile machines || 2.0 || 2.3 || 2.8 |
| Large presses, calenders, forging machines, wire drawing machines || 2.8 || 3.2 || 4.0 |
| Heavy calender, other heavy machines || 3.4 || 4.0 || 4.8 |