The speed reducer is a separate component consisting of the gear drive, worm drive, and gear-worm drive enclosed in a rigid housing. It is often used as a reduction gear between the driving link and the work machine. The speed reducer plays a role in matching the rotational speed and transmitting torque between the driving link and the working machine or the actuator and is widely used in the rolling mill.
The working characteristics of the speed reducer are low speed, heavy load, large impact load, frequent impact times, and continuous operation. With the rapid development of rolling steel industry, the continuous expansion of steel products, the increase of production, the increase of rolling speed and the increase of rolling load, the rolling gear transmission device is required to have sufficient bearing capacity, that is, with high strength, high precision, high life and high reliability.
Therefore, modern large and medium-sized rolling mill gears generally use fine-finished hard-toothed and medium-hardened involute cylindrical gears, and adopts design and manufacturing techniques such as gear shaping, deep carburizing and shot peening. The reducer of the welded structure is also used more. The reducer housing and the cover are welded, and the welded large gear structure gradually replaces the cast gear and the ring gear structure.
Applicable conditions for speed reducer of rolling mill:
1) Speed of high-speed shaft is less than 1500 r/min. The gear circumferential velocity is less than 25m/s.
2) The working environment temperature of the reducer is - 10-40 C. (Heating or cooling devices are required when the temperature is lower than + 5 ~C or higher than + 30 ~C).
3) It can be operated in one direction or in both positive and negative directions.
Type, Characteristics and Applicable Speed Reducer
In the rolling mill transmission, the function of the speed reducer is to change the higher rotational speed of the electric motor to the required rotational speed of the roller in order to select a lower-priced high-speed motor in the main transmission. In general, a speed reducer is used when the roll speed is less than 200 to 250 r/min. If the roll speed is greater than 200 to 250 r/min, it is more suitable to use a low-speed motor without a speed reducer.
The function of the gear base is to transfer and distribute the torque to each roll of the working machine seat. When the roll of the work machine base is driven by a motor, the motion and torque transmitted by the motor or reducer are generally assigned to two rolls or three rolls. The compound gearbox is the gearbox in which the speed reducer and the gear unit are assembled. This structure is compact and lighter than the gear base and reducer. However, due to manufacturing and transportation constraints, the composite gearboxes are typically used on rolling mills with roll diameters less than 500 mm.