The tunnel boring machine reducer is used for low-speed and high-torque transmission equipment. The principle is to use the electric motor, internal combustion engine, motor or other high-speed power to mesh the gear with a small number of teeth on the input shaft of the tunnel boring machine reducer with the large gear on the output shaft, thereby achieving the purpose of deceleration; the ratio of the number of teeth of the large and small gears is the transmission ratio.
The tunnel boring machine reducer is an independent component composed of gear transmission, worm transmission, and gear-worm transmission enclosed in a rigid housing. It is often used as a reduction transmission device between the prime mover and the working machine!
There are many types of reducers for tunnel boring machines, such as involute cylindrical gear reducers, double arc cylindrical gear reducers, cycloid pinwheel reducers, NGW planetary gear reducers, three-ring tunnel boring machine reducers, arc cylindrical worm reducers, etc. Standard tunnel boring machine reducers should be used first in the design to facilitate design, manufacturing, repair and replacement.
We often see cooling fans installed on the high-speed shaft of the tunnel boring machine reducer. As we all know, the purpose of installing cooling fans is to enhance cooling. Today, Brother Xiu will talk to you about cooling fans.
1. Several basic concepts
a) Hard tooth surface and soft tooth surface gears. According to the hardness of the tooth surface, people usually divide gear transmission into two categories, namely hard tooth surface gear transmission and soft tooth surface gear transmission. The tooth surface hardness is greater than 350HBS, which is called hard tooth surface gear, and the tooth surface hardness is less than 350HBS, which is called soft tooth surface gear. The heat treatment method for soft tooth surface is generally normalizing and tempering, and the heat treatment method for hard tooth surface gear is generally carburizing and quenching. Under the same load capacity, the volume of the soft tooth surface gearbox is much larger than that of the hard tooth surface gearbox.
b)
b) Thermal power concept: The actual power of the gearbox when it is in continuous operation does not exceed a certain calculated oil temperature (such as 90°C). Thermal power is generally not considered for soft-toothed gear transmission (because of low load capacity, large volume, and low temperature), while thermal power must be considered for hard-toothed gears (high load capacity, small volume, and high temperature).
c) Gearbox heating: When selecting a hard-toothed tunnel boring machine reducer, an important parameter is thermal power. The thermal power of the tunnel boring machine reducer is closely related to its heat dissipation. To improve the thermal power, the heating problem in the box should be solved first. During the hot operation of the tunnel boring machine reducer (i.e. the heating and heat dissipation process), a large amount of heat is generated due to meshing loss, bearing loss, oil stirring loss, sealing loss, etc., which causes the tunnel boring machine reducer to increase in temperature due to excessive power loss, limiting the normal function of the system and having a great impact on the tunnel boring machine reducer system. To give full play to the performance of the tunnel boring machine reducer, a key factor is how to improve the thermal power. Improving the thermal power of the tunnel boring machine reducer is mainly achieved by cooling the tunnel boring machine reducer system, increasing its heat dissipation and the circulation of lubricating oil. Usually, the additional cooling of the tunnel boring machine reducer mainly includes: cooling fan, water cooling coil, and forced lubrication system.
2 Three ways of heat transfer: conduction, convection and radiation
a) Heat conduction: When there is a temperature difference in a continuous medium, or when two objects with different temperatures are in direct contact and there is no visible macroscopic material flow in the objects, the heat transfer phenomenon that occurs is mostly heat conduction.
b) Convection: Heat transfer that occurs when there is fluid and macroscopic movement of the fluid is called convection.
c) Radiation: When an object is heated, it emits thermal radiation energy. High-temperature objects lose heat while low-temperature objects gain heat. This method is called radiation heat transfer.
3. Heat transfer method of tunnel boring machine reducer
a) Heat conduction: Heat conduction and heat transfer are carried out between the base of the tunnel boring machine reducer and the foundation, which exchanges heat and reduces the temperature of the tunnel boring machine reducer.
b) Radiation: The high-temperature reducer housing of the tunnel boring machine transfers heat through radiation from the outer surface, transferring the heat to the air, and the air carries away the heat through its flow.