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80% of the bearings are damaged early, which may be caused by incorrect bearing installation

Time:2021-06-17 Views:544
Whether it's bearings or machining, your bearings often have problems. Today, the China bearing network (referred to as: China bearing network) to seriously and sincerely inform you: in fact, 80% of the bearing early failure because there is no correct installation. The correct installation of the bearing can not only increase the service life of the bearing, reduce the cost, but also greatly improve the production efficiency. Therefore, it is urgent to learn the correct bearing installation knowledge.


How to install it correctly? We share a valuable article on bearing installation for you. We will have a certain understanding of bearing installation and extend the service life of bearings in a few minutes.


Bearing is used to support the components, but also used to support the rotating parts on the shaft. The types of bearings are divided into sliding bearings and rolling bearings according to the friction properties; According to the direction of bearing load: there are centripetal bearing, push bearing, centripetal thrust bearing, etc.


1. Assembly of sliding bearing


Sliding bearing is a kind of bearing with sliding friction property, which is characterized by stable operation, low reliable noise, heavy load and large impact load. It can be divided into integral type, split type and tile type according to the structure form.


(1) Assembly of integral sliding bearing


Integral sliding bearing is commonly known as shaft sleeve, and is also the simplest form of sliding bearing. It is mainly assembled by pressing and hammering. In special occasions, hot mounting method is adopted. Most of the sleeve is made of copper or cast iron. It should be carefully assembled. It can be assembled by wooden hammer or hammer pad block. If the tolerance of interference dimension is large, press in with a press. No matter whether it is knocked in or pressed in, it must be prevented from tilting. After assembly, the oil tank and oil hole shall be in the required position.


For the bearings deformed after assembly, the inner hole shall be trimmed. Reamers with smaller sizes can be used for cutting, and for larger ones, scraping shall be used. Meanwhile, the clearance between the shaft and the shaft shall be controlled within the tolerance range. In order to prevent the sleeve from turning during the operation, the contact surface of the shaft sleeve and the box body is equipped with locating pin or riding screw. When the hardness of the box and sleeve material is different, it is easy to make the bit lean to the soft material side. The solution is: first, the sample is used to punch the hard material while punching the hole before drilling, and the other is to use short bit to increase the steel of the drill bit.


(2) Assembly of split bearing


Split bearing, also known as opposite bearing, has the characteristics of simple structure, convenient adjustment and disassembly. Two bearing shells are inserted on the bearing shells, and reasonable clearance is adjusted by using gasket at the joint.


① Assembly of bearing shells and bearing bodies


The contact between the upper and lower bearing shells and the bearing bore must be good. If it does not meet the requirements, the bearing bore of the thick wall bearing shell shall be taken as the benchmark, and the back of the bearing bush shall be scraped, and the steps at both ends of the bearing shell shall be close to both ends of the bearing body. Thin wall bearing can be scraped if the middle split surface of bearing shell is about 0.1mm higher than that of bearing body.


② Bearing shells are installed in bearing body, no displacement is allowed in radial or axial direction. Usually, steps at both ends of bearing shells are used to stop positioning or locating pin positioning.


③ The matching scraping of bearing shells


The split bearing shells are generally used with the matching shaft grinding points. Generally, they are first scraped down the bearing shells, and then the bearing shells. In order to improve the efficiency, the bearing shells and covers can not be installed when scraping the lower bearing shells. When the contact points of the current bearing shells basically meet the requirements, the upper bearing shells and upper cover are compressed. When the upper bearing shells are scraped, the contact point of the lower bearing shells is further modified. The tightness of the shaft can be adjusted by changing the thickness of the gasket with the increase of scraping times. When the bearing cover is fastened, the shaft can be easily turned without obvious clearance. The contact point meets the requirements, and the scraper is completed.


④ Measurement of bearing clearance


The size of bearing clearance can be adjusted by the gasket at the split surface or directly scraped the bearing bush. The method of lead pressing is usually used to measure the bearing clearance. Several segments of lead wires with diameter larger than the bearing clearance are taken and placed on the journal and the center split surface. Then tighten the nuts to make the split face compact, then screw off the nut, take off the bearing cover, carefully take out the flattened lead wire, and measure the thickness by micrometer. According to the average thickness of the lead wire, the bearing clearance can be known. The clearance of general bearings shall be 1.5 ‰ - 2.5 ‰ (mm) of shaft diameter, and smaller clearance value shall be taken when the diameter is larger. If the bearing clearance with shaft diameter of 60mm should be between 0.09-0.15mm.


2. Assembly of rolling bearing


Rolling bearing has the advantages of small friction, small axial size, convenient replacement and simple maintenance.


(1) Technical requirements for assembly


① The end face marked with the code number of rolling bearing shall be installed in the visible direction for checking and checking during replacement.


② The radius of the circular arc at the steps of the journal or shell hole shall be smaller than that of the corresponding part on the bearing.


③ After the bearing is assembled in the shaft and the shell hole, there shall be no deflection.


④ In the two bearings of the coaxial, one must move with the shaft when it expands.


⑤ When assembling rolling bearings, dirt must be strictly prevented from entering the bearing.


⑥ The assembled bearing shall be flexible in operation, with small noise and working temperature not exceeding 65 ℃.


(2) Assembly method


When assembling bearings, the most basic requirement is to make the added axial force directly act on the end face of the sleeve ring of the bearing (when installed on the shaft, the added axial force shall directly act on the inner ring, and the added force shall be directly applied on the outer ring when installed on the hole). Try not to affect the rolling body. The methods of assembly include hammer, press assembly, hot assembly, freezing assembly, etc.


① Hammering


The method of hammering with copper rod and some soft materials shall be used. It is necessary to pay attention not to make the foreign matters such as copper end fall into the bearing raceway, and do not directly knock the inner and outer rings of the bearing with a hammer or punch barrel, so as to avoid affecting the bearing matching accuracy or causing bearing damage.


② Assembly method of screw press or hydraulic press


For bearings with large interference tolerance, they can be assembled by screw press or hydraulic press. Before pressing, the shaft and bearing shall be leveled and coated with a little lubricating oil. The pressing speed should not be too fast. The pressure shall be removed quickly after the bearing is in place to prevent damage to the bearing or shaft.


③ Hot charging method


The hot installation method is to heat the bearing in oil to 80 ℃ -100 ℃, make the bearing bore swell and then set it on the shaft, which can prevent the shaft and bearing from damage. For bearings with dust caps and sealing rings, the heat installation method is not applicable for bearings with grease inside.


(3) tapered roller bearing clearance is adjusted after assembly. The main method is to adjust gasket, screw adjustment and nut adjustment.


(4) When assembling thrust ball bearings, the tightening ring and loose ring shall be separated first. The diameter of the inner diameter of the tightening ring is slightly smaller. The assembled tightening ring and the shaft are kept relatively static when they are working. It always depends on the steps or hole end faces of the shaft, otherwise the bearing will lose rolling effect and accelerate the wear.


3. Rolling bearing instructions


The bearing shall be installed with uniform force and shall not be hammered directly. For example, if the fit interference is large, the bearing shall be heated in an air heater or oil furnace with automatic temperature control, and the heating temperature shall be strictly controlled at 120 ° following.


Bearings with nylon cage can be at -40 °- one hundred and twenty ° Continuous and stable operation in the next long term, at 150 ° The working time should not exceed 4 hours, and the transient temperature peak value can reach 180 °。 The storage room for bearing shall be clean, and the dry storage shall not be the same as chemical products, and the relative humidity shall not exceed 65%, and the bearing shall not be stored on the ground.


(1) Installation and use of deep groove ball bearing


The bearing shall be installed with uniform force and shall not be hammered directly. For example, if the fit interference is large, the bearing shall be heated in an air heater or oil furnace with automatic temperature control, and the heating temperature shall be strictly controlled at 120 ° following.


Bearings with nylon cage can be at -40 °- one hundred and twenty ° Continuous and stable operation in the next long term, at 150 ° The working time shall not exceed 4 hours, and the transient temperature peak value shall not exceed 180 °。 The storage room for bearing shall be clean, and the dry storage shall not be the same as chemical products, and the relative humidity shall not exceed 65%, and the bearing shall not be stored on the ground.


The bearings in stock shall be cleaned again every year for rust proof packaging.


(2) Installation and use of angular contact ball bearing


The bearing shall be installed with uniform force and shall not be hammered directly. For example, if the fit interference is large, the bearing shall be heated in an air heater or oil furnace with automatic temperature control, and the heating temperature shall be strictly controlled at 100 ° following.


Bearings with nylon cage can be at -40 °- one hundred and twenty ° Continuous and stable operation in the next long term, at 150 ° The working time shall not exceed 4 hours, and the transient temperature peak value can reach 180 °。 The storage room for bearing shall be clean, and the dry storage shall not be the same as chemical products, and the relative humidity shall not exceed 65%, and the bearing shall not be stored on the ground.


(3) Installation and use of the self aligning roller bearing


The user shall select the appropriate fit and bearing force clearance according to the requirements. Please check the bearing code after unpacking.


Before bearing installation, if grease is needed in the bearing, the grease must be clean and proper.


When installing, it is advisable to not hammer the inner ring, outer ring end face and roller directly to avoid cracking the inner ring or middle and small stop. The user should normally heat the bearing into mineral oil to 90 °- one hundred ° Install the spindle immediately. Do not use local spray burning method for bearings, and users should also use special sleeve to install them when it is difficult to "hot install".


The bearing should be well sealed and dustproof device and lubrication, and oil should not be cut off.


The bearing warehouse shall be clean and dry without environmental pollution, bearing stacking shall not be placed on the ground, and the packing shall be free of damage. Bearings in stock for more than one year must be cleaned and oiled again.


(4) Installation and use of thrust adjusting roller bearing


When installing the bearing, the bearing oil seal shall be cleaned and then coated with clean high-quality lubricating oil.


When installing the bearing, the force shall be uniform and shall not be hammered. If the fit interference is large, the bearing should be heated to 90% in mineral oil °- one hundred ° After that, install immediately.


The storage room for bearing shall be clean and clean, with relative humidity not exceeding 65%.


The bearing in stock shall be cleaned and oiled again every year, and the oil seal packaging shall be kept in good condition.


When using bearings, good sealing and dust-proof devices shall be provided, and the working conditions shall be checked frequently.


(5) Installation and use of cylindrical roller bearing


The bearing is of the separation type, and the user can adjust the clearance according to the needs.


Before using, the bearings shall be cleaned with gasoline or kerosene and well lubricated.


During bearing installation, the bearing shall be pressed into the parts, and it is strictly forbidden to knock.


The bearing storage place shall be clean and ventilated to avoid humidity. Bearings that need to be kept for a long time shall be rust proof regularly.


(6) Installation and use of thrust ball bearing


When installing the bearing, the bearing seal shall be removed, cleaned and then coated with clean high-quality lubricating oil.


When installing the bearing, the force shall be uniform and shall not be hammered. If the fit interference is large, the bearing should be heated to 90% in mineral oil °- one hundred ° After that, install immediately.


The storage room for bearing shall be clean and clean, with relative humidity not exceeding 65%.


The bearing in stock shall be cleaned and oiled again every year, and the oil seal packaging shall be kept in good condition.


When using bearings, good sealing and dust-proof devices shall be provided, and the working conditions shall be checked frequently.


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