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Selection of lubrication mode 1. A few small reducers with low speed (v < 0.5m/s) adopt grease lubrication, and most reducer gears adopt oil lubrication. Oil-immersed lubrication can be used for gear transmission whose circumferential velocity is less than 12 m/s. The gear is immersed in oil. When the gear rotates, the oil glued to it is brought to the meshing area for lubrication. At the same time, the oil in the oil tank is thrown onto the wall of the box to help heat dissipation. In order to avoid excessive power consumption of oil-immersed lubrication and ensure full lubrication of gear teeth meshing zone, the depth of immersion in oil should not be too deep or too shallow. Generally, the depth of oil-immersion should be moderate with one tooth height of oil-immersed gear and shallow with high speed (about 0.7 times tooth height), but not less than lOmm; bevel gear should be the whole. The tooth width (at least half of the tooth width) is immersed in oil. For multi-stage transmission, in order to immerse large gears of all levels in oil, the oil immersion depth of low-speed large gears can be larger. When the circumferential velocity v=0.8-12m/s, the dividing circle radius of 1/6 gears can be reached; when v<0.5-0.8m/s, the dividing circle radius can reach L v=">12m/s or worm circumferential velocity v>10m/s, the oil immersion should not be used. Lubrication, because the oil adhering to the gear will be thrown out by centrifugal force and sent to the meshing area, and stirring too much will make the oil temperature rise, oil foaming and oxidation, etc. to reduce lubrication performance. At this time, it is appropriate to use oil injection lubrication, that is, using oil pump (pressure about 0.05-0.3 MPa) with the help of pipes will not be high lubrication but rather heavy working conditions of heavy reducer and need a lot of lubricating oil for cooling reducer. Because fuel injection lubrication requires special pipelines, filters, cooling and oil regulation devices, it is more expensive. For worm reducer, when the circumferential velocity of worm is less than 4-5m/s, it is suggested that the worm be placed below (lower type); when v > 5m/s, it is suggested that the worm be placed above (upper type).
Selection of Lubricating Oil Viscosity
The lubricating oil viscosity of gear reducer can be selected according to the circumferential velocity V of high speed gears: medium extreme pressure gear oil N320 can be selected for V < 2.5m/s; medium extreme pressure gear oil N220 can be selected for V > 2.5m/s or for cyclic lubrication. If the working environment temperature is below 0 C, the lubricant must be heated above 0 C first. The lubricating oil viscosity of worm reducer can be selected according to the sliding speed s v: N680 extreme pressure oil can be used for s mvs/2 and N220 extreme pressure oil can be used for S V > 2m/s. The viscosity of worm reducer should be increased by 30%.
Rolling bearings in lubrication reducers of bearings are commonly used to lubricate the oil of gears (or worm wheels) within deceleration 29. The commonly used lubrication methods are as follows:
1. Splash lubrication can be used as long as the circumferential velocity of an oil-immersed gear is greater than or equal to 1.5-2m/s in the splash lubrication reducer. When V > 3m/s, the splashed oil can form oil mist and splash directly into the bearing chamber. Sometimes, because the circumferential velocity is not high enough or the oil viscosity is high, it is not easy to form oil mist. In order to make lubrication reliable, oil transmission ditches are often made on the joint surface of the box seat, so that the oil splashed on the inner wall of the box cover gathers in the oil ditch, and then flows into the bearing chamber for lubrication. Chamfers are made at the contact point between the inner wall of the box cover and its joint surface. It is convenient for oil to flow into the oil ditch. When it is difficult to install oil conveying groove to collect oil mist into bearing chamber, oil diversion groove lubrication or oil diversion groove lubrication are also used.
2. Scraper lubrication When the circumferential velocity of oil-immersed gears is less than 1.5-2m/s, oil splashing cannot occur; even if the circumferential velocity of the lower worm is greater than 2m/s, it is difficult for the splashed oil to enter the bearing chamber of the worm shaft due to the low position of the worm and the vertical intersection of the space with the worm axis. At this time, scraper lubrication can be used. The scraper is used to scrape oil from the end face of the worm wheel flange and then flow into the worm wheel shaft bearing through the oil delivery groove. In the scraper lubrication device, the clearance between the scraper and the rim should be maintained (about 0.5mm), so the end runout of the rim and the axial movement of the shaft should also be limited.
3. Oil-immersed lubricated bearings of lower worm are often lubricated in oil. As mentioned earlier, the oil level should not generally be higher than the center of the rolling element below the bearing. When the circumferential velocity of oil-immersed gears is too low to form oil mist by flying vinegar, or it is difficult to lead into bearings, or to make bearings immersed in oil, grease lubrication can be used. Lubricating grease is usually filled into the bearing chamber at assembly time, and its loading capacity generally does not exceed 1/3-1/2 of the space of the bearing chamber. Later, it is added 1-2 times a year. When grease lubrication is used, oil rings or other internal sealing devices should be installed on the inner side of the bearing chamber to prevent oil from entering the bearing chamber to dilute the grease. Calcium base grease can be selected for Grease-Lubricated bearings at low speed and below 70 C, and sodium base grease or calcium-sodium base grease at high temperature. The d n value (d is journal diameter, mm; n is working speed, r/rain) is high (>40000mm r/min) or lithium molybdenum disulfide base grease can be selected for complex load conditions. Aluminum base grease or barium base grease can be used in wet environment but not. Sodium base grease which is decomposed in water should be selected. If sliding bearing is used in reducer, because the viscosity of transmission oil is too high to be used in rotary cap oil cup, a separate lubrication system should be adopted. At this time, the appropriate lubrication method and oil should be selected according to the working conditions of sliding bearing, such as load, sliding speed and so on. Sealed reducer of reducer generally needs to be sealed at the shaft extension, bearing indoor side, box joint surface and bearing cover, inspection hole and oil drain hole joint surface.
1. Sealing at the extension of the shaft
(1) Felt ring seals utilize the compression effect of rectangular cross-section felt rings embedded in trapezoidal grooves to prevent lubricant leakage and invasion of external impurities and dust into bearing chambers. Press the blanket ring with a pressure plate to adjust the radial sealing force and replace the blanket ring. Felt ring seal is simple and inexpensive, but its friction on the contact surface of journal is serious. It is mainly used for grease lubrication and oil lubrication with low circumferential velocity of Journal (generally not more than 4-5m/s).
(2) The skin-bowl seal uses the elasticity of the lip-shaped structure part of the J-shaped sealing ring and the fastening force of the coil spring ring to make the lip-shaped part close to the surface of the shaft and play a sealing role. The sealing ring is equipped with a metal skeleton, which is fixed axially by the cooperation of the periphery and the hole; the skeleton-free sealing field must be axially used. Fixed. The sealing effect on both sides of the sealing ring is different. If the main purpose is to seal oil, the seal lip should be against the bearing; if the main purpose is to prevent foreign invasion, the seal lip should carry the bearing; if you want to have both leak-proof and dust-proof capabilities,* use two reverse-positioned sealing rings. The cup seal is reliable in operation, good in sealing performance and easy to install and replace. It can be used for oil lubrication and grease lubrication. For the Journal of finishing car, the circumferential velocity V is less than 10 m/s, and for the polished journal V is less than 15 m/s.
(3) The clearance sealing device of clearance type is simple in structure, and the circumferential speed of the journal is generally not limited, but the sealing is not reliable enough. It is suitable for bearings with grease lubrication, oil lubrication and clean environment.
(4) The centrifugal seal installs an oil-throwing ring on the shaft, opens a groove on the shaft, and uses centrifugal force to flush the oil to flow back along the radial direction. This kind of structure is usually combined with clearance seal and is only suitable for oil lubrication with circumferential velocity v (> 5m/s).
(5) Labyrinth seal is also effective for oil lubrication and grease lubrication, but its structure is complex and it is suitable for high speed.
2. It is common to apply sealant seal on the joint surface of the box cover and the box seat. It is also common to open the oil ditch at the same time on the joint surface of the box seat so that the oil infiltrated into the joint surface can flow back to the oil pool in the tank through the oil return ditch and the oil return channel to increase the sealing effect.
3. Paper-sealed oil pad or leather-sealed oil ring should be added between sealing inspection hole cover plate, oil drain screw, oil mark and joint surface of tank body in other parts. The sealing gasket should be encrypted between the screw bearing end cap and the box body. The O-shaped rubber seal ring is commonly used between the embedded bearing end cap and the box body to prevent leakage.
