Composition and structure of reducer

2022-06-23
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Composition and structure of reducer introduction to reducer is an independent transmission component used to reduce speed, transmit power and increase torque. The reducer is an independent closed transmission device between the prime mover and the working machine. It is used to reduce the speed and increase the torque to meet the work needs. It is also used to increase the speed in some occasions. It is called the speed increaser. When selecting reducers, the external dimensions, transmission efficiency, bearing capacity, quality and price of reducers of different types and varieties shall be compared according to the selection conditions, technical parameters, power machine performance, economy and other factors of the working machine, so as to select the most suitable reducer. The reducer is a kind of relatively precise machinery. The purpose of using it is to reduce the speed and increase the torque

basic structure reducer is mainly composed of transmission parts (gear or worm), shaft, bearing, box and its accessories. Its basic structure has three parts:

1. Gear, shaft and bearing combination

the pinion is integrated with the shaft, which is called the gear shaft. This structure is used when the gear diameter is not closely related to the shaft diameter. If the shaft diameter is D and the gear root circle diameter is DF, this structure should be used when df-d ≤ 6 ~ 7mn. When df-d> 6 ~ 7mn, the gear and shaft are separated into two parts, such as low-speed shaft and large gear. At this time, the gear is connected with the circumferential fixed flat key of the shaft, and the parts on the shaft are axially fixed by the shaft shoulder, shaft sleeve and bearing cover. Deep groove ball bearings are used for both shafts. This combination is used to bear radial load and axial load not

. When the axial load is large, the combined structure of angular contact ball bearing, tapered roller bearing or deep groove ball bearing and thrust bearing shall be adopted. The bearing is lubricated by the thin oil splashed when the gear rotates. The lubricating oil in the oil pool in the box seat is splashed on the inner wall of the box cover by the rotating gear, flows along the inner wall to the groove of the box surface, and then flows into the bearing through the oil guide groove. When the gear is immersed in oil, the circumferential speed υ When ≤ 2m/s, the bearing shall be lubricated with grease. In order to avoid the grease being washed away by the thin oil that may splash, the oil retaining ring can be used to separate it. In order to prevent the loss of lubricating oil and external dust from entering the box, a sealing element is installed between the bearing end cap and the extended shaft

2. Box

box is an important component of reducer. It is the base of transmission parts and should have sufficient strength and stiffness

the box body is usually made of gray cast iron. For the reducer with heavy load or impact load, the coating of this product can initially form a uniform and complete film load on the plastic surface, and the cast steel box body can also be used. In order to simplify the process and reduce the cost, steel plate welded box can be used for the reducer produced individually

grey cast iron has good casting and vibration damping properties. In order to facilitate the installation and disassembly of shafting components, the box body is made into a horizontal split type along the axis. The upper case cover and the lower case are connected into a whole by bolts. The connecting bolt of the bearing seat shall be as close to the bearing seat hole as possible, and the boss near the bearing seat shall have enough bearing surface to place the connecting bolt and ensure the wrench space required for tightening the bolt. In order to ensure that the box has sufficient rigidity, support ribs are added near the bearing holes. In order to ensure the stability of the reducer on the foundation and minimize the machining area of the box base plane, the box base generally does not adopt a complete plane

3. Reducer accessories

in order to ensure the normal operation of the reducer, in addition to paying enough attention to the structural design of the gear, shaft, bearing assembly and box, it should also consider the reasonable selection and design of auxiliary parts and components such as filling and draining oil for the reducer lubricating oil pool, checking the oil level height, precise positioning and hoisting of the box cover and box seat during processing, disassembly and maintenance

1) the inspection hole is to check the engagement of transmission parts and inject lubricating oil into the box. The inspection hole shall be set at the appropriate position of the box. The inspection hole is set at the top of the upper case cover where the gear meshing part can be directly observed. At ordinary times, the cover plate of the inspection hole is fixed on the box cover with screws

2. The surfaces of the exposed parts of the testing machine that are not painted should often be coated with anti rust oil

2) when the ventilator reducer works, the temperature in the box increases, the gas expands, and the pressure increases. In order to make the hot expanded air in the box be discharged freely, so as to maintain the pressure balance inside and outside the box, so as not to cause the lubricating oil to leak along the sub box surface or other gaps such as shaft extension seals, a ventilator is usually installed on the top of the box

3) the bearing cover is used to fix the axial position of the shafting components and bear the axial load. Both ends of the bearing seat hole are closed with the bearing cover. There are two types of bearing covers, flange type and embedded type. It is fixed on the box with hexagon bolts, and the bearing cover at the extended shaft is a through hole, which is equipped with a sealing device. The flange bearing cover has the advantages of convenient disassembly, assembly and adjustment of bearings, but compared with the embedded bearing cover, it has more parts, larger size and uneven appearance

4) locating pin in order to ensure that the accuracy of bearing seat hole manufacturing is maintained during each disassembly and assembly of the box cover, the locating pin shall be installed on the connecting flange between the box cover and the box seat before finishing the bearing hole. It shall be placed on the connecting flanges at both longitudinal sides of the box. The symmetrical box shall be symmetrically arranged to avoid wrong installation

5) oil level indicator check the height of oil level in the oil pool in the reducer, always keep a proper amount of oil in the oil pool, and generally install the oil level indicator at the position where the box is easy to observe and the oil level is relatively stable

6) when replacing the oil drain plug, drain the dirty oil and cleaning agent. The oil drain hole shall be set at the bottom of the tank seat and the lowest position of the oil pool. At ordinary times, the oil drain hole shall be blocked with a plug. A leak proof gasket shall be added between the oil drain plug and the junction surface of the tank

7) in order to strengthen the sealing effect, the opening screws are usually coated with water glass or sealant on the split surface of the box during assembly, so it is often difficult to open the cover due to tight cementation during disassembly. For this reason, it is often used to machine ~ 2 screw holes at the appropriate position of the connecting flange of the box cover, and screw in the box opening screws with cylindrical end or flat end. Turn the case opening screw to jack up the upper case cover. The small reducer may not be equipped with case opening screws. When opening the cover, use a screwdriver to pry the case opening cover. The size of the case opening screws can be the same as the flange connecting bolts

basic classification 1. Reducers can be divided into general reducers and special reducers according to their applications, and their design, manufacturing and use characteristics are different. In the s of the 20th century, the reducer technology in the world has made great progress, which is closely combined with the development of the new technological revolution. Its main types: gear reducer; Worm reducer; Gear worm reducer; Planetary gear reducer

2. General reducers have experimental data files, which can save helical gear reducers (including parallel shaft helical gear reducers, worm gear reducers, bevel gear reducers, etc.), planetary gear reducers, cycloid pin gear reducers, worm gear reducers, planetary friction mechanical stepless speed changers, etc. in the way of access, which often uses databases

1) cylindrical gear reducer

single-stage, two-stage and above two-stage. Layout: deployable, shunt and coaxial

2) bevel gear reducer

is used when the position of input shaft and output shaft intersect

3) worm gear reducer

is mainly used for occasions with transmission ratio of I 10. When the transmission ratio is large, the structure is compact. Its disadvantage is low efficiency. At present, Archimedes worm reducer is widely used

4) gear worm reducer

if the gear transmission is at the high-speed level, the structure is compact

if the worm drive is at the high-speed stage, the efficiency is higher

5) planetary gear reducer

has high transmission efficiency, wide transmission ratio range, transmission power of 12w~50000kw, small volume and weight

3. Types of common reducers

1) the main feature of worm gear reducer is that it has reverse self-locking function and can have a large reduction ratio. The input shaft and output shaft are not on the same axis or plane. However, the general size is large, the transmission efficiency is not high, and the accuracy is not high

2) the harmonic drive of harmonic reducer uses the controllable elastic deformation of flexible elements to transmit motion and power. It has small volume and high precision, but its disadvantages are that the flexible wheel has limited service life, is not resistant to impact, and its rigidity is poor compared with that of metal parts. The input speed cannot be too high

3) planetary reducer has the advantages of compact structure, small return clearance, high precision, long service life and large rated output torque. But the price is a little expensive. Reducer: in short, after the power of general machines is designed and manufactured, its rated power will not change. At this time, the greater the speed, the smaller the torque (or torque); The smaller the speed, the greater the torque

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