The main function of the reducer is to change the speed and torque between the prime mover and the actuator, and is widely used in the machinery industry and the metallurgical industry.
There are many types of gear reducer transmission devices, mainly cylindrical gear reducer, cone-cylindrical gear reducer, planetary gear reducer, gear-worm reducer, special gear reducer, etc.
This article shares the main types of gear reducer transmission, different installation methods, comparison of lubrication and sealing methods.
Main types of gear reducers
1.1 Cylindrical gear reducer
Cylindrical gear reducer is mainly divided into involute cylindrical gear reducer and arc cylindrical gear reducer.Among them, involute cylindrical gears are widely used and can be divided into straight teeth, helical teeth and herringbone teeth.
The degree of coincidence of helical teeth is greater than that of straight teeth, and the noise and wear are smaller. They are generally used for transmission of heavy-duty machinery; herringbone teeth have low manufacturing accuracy and are not suitable for wide use in various metallurgical machinery.When selecting a reducer, it should be selected according to actual factors such as peripheral speed, load conditions, and working conditions.
At present, the involute cylindrical gear reducer has the advantages of easy processing, convenient manufacturing and assembly, high precision, and the change of center distance does not affect its normal meshing.
Due to its large carrying capacity range, both the nominal input power and the nominal output torque range, it is widely used in my country's metallurgy, mining, transportation and other equipment.Because the gear teeth are in line contact, this type of reducer has higher requirements for the accuracy and rigidity of the parts of the gear mechanism.
1.2 Cone-cylindrical gear reducer
Cone-cylindrical gear reducer is a transmission device used for vertical arrangement of input shaft and output shaft.The first-stage transmission of this type of gear reducer is a spiral bevel gear made by Gleason, and other tooth profiles can also be used. The first and third-stage transmission are involute cylindrical helical gears.
The gears and bearings of this type of reducer generally use splash lubrication and natural cooling.This type of reducer has the advantages of high carrying capacity, low noise, small size, light weight, high efficiency and long service life. It is widely used in metallurgy, coal, transportation, building materials and other mechanical equipment.
1.3 Planetary gear reducer
There are many types of planetary gear reducers, mainly including universal planetary gear reducers, various small tooth difference reducers, harmonic gear reducers and three-ring reducers.
The advantage of this type of reducer is that it can be made into single-stage, double-stage and multi-stage reducers, so the transmission ratio range is large, and it has the characteristics of compact structure, light weight, large carrying capacity, and small outline size.However, its structure is complex, manufacturing accuracy is high, assembly and maintenance are difficult, and the price is high.
2.1 Installation method of gear reducer
1) Fixed installation with solid shaft
This installation method is to connect the output shaft of the gear reducer with metallurgical machinery through couplings, sprockets, gears, pulleys, etc., and install the reducer firmly on a solid structure by the anchor bolts at the bottom of the gear reducer , On a vibration-free basis.At present, most gear reducers can adopt this installation method.
For large gear reducers, threaded holes should be machined on the body feet to adjust the installation position with adjusting bolts; for gear reducers of luffing mechanism, pins should also be used for locking to prevent movement during installation .
2) Single-point floating installation of hollow shaft
This installation method uses the output shaft of the gear reducer as a hollow shaft and is connected to the transmission shaft of the working machine through an expansion sleeve. The entire drive device, including the motor, coupling, brake, and reducer, is installed on the support of the transmission device. Seat, and then supported by a ball hinge or bearing.
The installation principle is that the bearing point of the spherical hinge deviates from the center of gravity of the transmission device by a certain distance. In the working state, the bending moment caused by the eccentricity of the support point can be balanced with the bending moment caused by the load of the drive device. Therefore, the transmission shaft is not affected in theory. Additional force.
3) Hollow shaft suspension installation
This installation method is to connect the output shaft of the reducer and the metallurgical machinery shaft with an expansion sleeve, and the support is completed by the output shaft and another torsion rod.This installation method is relatively simple, saves floor space, and can reduce the weight of the whole machine, and is suitable for transmission devices that transmit power from a vertical direction.
2.2 Lubrication method of gear reducer
The lubrication effect has a great influence on the gear reducer.If the lubrication conditions are not good, the heat generation of the gear reducer will increase and its carrying capacity will decrease.Therefore, the lubricating oil and the amount of oil must be selected correctly to effectively ensure the normal operation of the gear reducer transmission device and extend its service life.
Under normal circumstances, the lubrication method adopts oil pool lubrication and natural cooling; but for high-power gear reducers or when the thermal power is not enough, pressure circulating oil lubrication or additional cooling devices can be used for cooling.
Under normal operating conditions, when the ambient temperature is (0~35)℃, or when circulating oil lubrication is used, medium-duty industrial gear oil 220# is recommended; when the ambient temperature is (35~50)℃, it is recommended for selection Load industrial gear oil 320#.In addition,The reducer is running for the first time400hAfter that, the lubricating oil should be replaced.
2.3 Sealing method of gear reducer
1) Skeleton oil seal
Most of the shaft seals of gear reducers generally use elastic sealing rings with lip edges. This sealing method has the characteristics of easy installation and good use effect, and standard parts are available.When oil seals are used in pairs, the space between the two oil seals should be filled with grease.
When using this method for sealing, it is required that the surface of the journal that matches the oil seal should be hardened or chrome-plated to ensure its hardness ≥ 30HRC.At the same time, in order to ensure that the surface roughness is controlled at Ra (0.25~0.63) μm, the cutting method can also be used for grinding during processing.
2) Combined seal
The combined sealing method adopts a triple sealing structure of sparse and plugging, which will not affect the lubrication of the parts and can effectively prevent leakage.The first seal is on the outside of the oil injection hole, and at the appropriate position inside the oil baffle (to ensure the oil level necessary for bearing lubrication), a return hole is drilled through the inside of the box to basically ensure the return of large flow lubricating oil. The smooth flow of oil.
In addition, between the first seal and the second seal, a second oil return hole is drilled directly below the hole in the box to ensure that the oil squeezed out from the small pores can flow back to the box.
The second seal is a set of sealing sheets composed of 3~5 sheets of thin steel plates with a thickness of (1.0~1.2) mm.Drill another oil return hole at the place where the sealing plate and the lower part of the end cover fit to ensure that the last remaining lubricating oil flows back into the box.
The third seal is a packing seal strip, which uses a new type of packing-carbon fiber, which is pressed between the shaft and the end cover.This kind of sealing material has good self-lubricity, heat resistance, corrosion resistance, long service life, and can effectively prevent oil seepage and dust for the gear reducer.