机械外文翻译---关于轴承和轴的相关知识

附录一Knowledge On The Bearings and ShaftThe bearings are fixed and reduce the load coefficient of friction in the process of mechanical transmission components. Can also say that when the other parts on the shaft relative motion, used to reduce the friction coefficient in the process of power transfer and fixed the mechanical parts to maintain the position of the shaft center. Bearings are important parts of modern machinery and equipment. Its main function is to support the mechanical rotating body to reduce the load coefficient of friction of the mechanical equipment in the transmission process. According to the different nature of friction of moving parts, bearings can be divided into two types of rolling bearings and plain bearings.Nano Lake, Italy, found a Roman vessel discovered early instance of ball bearings. The wooden ball bearings are used to support the rotating desktop. Ship construction in 40 BC. It is said that Leonardo da Vinci in the 1500 or so, a ball bearing through description. , There is a very important point is the ball collision, causing additional friction between the ball bearings of all kinds of immature factors. But can put the ball into a small cage to prevent this phenomenon. The 17th century, Galileo fixed ball ", or" cage ball "ball bearings did the earliest description. But then quite a long time, the bearings have been installed on the machine. The first patent on the ball channel the Carmarthen Philip Vaughan in 1794.In 1883, Friedrich Fischer proposed the idea of the use of suitable production machine grinding the same size, roundness accurate ball. This laid the foundation to create an independent bearing industry. In 1962, FAG the trademark has been modified and are still used today and become an integral part of the company in 1979.In 1895, Henry Timken designed the first tapered roller bearings, three years later obtained a patent and the establishment of the Timken Company.In 1907, SKF bearing factory Sven temperature Qwest designed the first modern self-aligning ball bearings.Study its role should be in terms of support, that the literal interpretation is used to bearing axis, but this is only part of its role in supporting its essence is to be able to bear the radial load. Can also be understood that it is used to a fixed axis. A fixed axis so that it can only achieverotation, and control of axial and radial movement. Motor without bearing the consequences is not work at all. Because the axis may be in any direction movement, the motor work requirements shaft only rotation. Impossible to realize the role of the drive, in theory, not only that, bearing also affect the transmission must be achieved in order to reduce this effect in the high speed shaft bearing lubrication, and some bearing lubrication, called pre-lubricated bearings, and the most of the bearing lubricant, the load at high speeds, due to the friction will not only increase energy consumption, even worse, is very easy to damage the bearing. Sliding friction into rolling friction is one-sided to say things because of the kind called plain bearings.Bearing the classification and described as follows:Equipped with a thin and long roller needle bearing (the length of the roller diameter of 3 to 10 times the diameter of generally not more than 5mm), therefore the radial structure is compact, its inner diameter and load capacity with other types of bearing the same minimum outside diameter, especially for supporting the results of radial installation dimensions restricted. needle bearing according to the use of different occasions, can be used without inner ring bearings or needle roller and cage assembly and bearing to match the journal surface directly as a bearing surface and shell holes, outer rolling surface in order to ensure the load capacity and running performance with a ring bearing the same shaft or shell holes on the raceway surface of the hardness, the machining accuracy and surface quality should be the bearing rings. use Combined needle roller bearings to the heart needle roller bearings and thrust bearing parts bearing units of the combination of its compact size, small, high precision rotation, can withstand high radial load to bear certain axial load. And the product structure in various forms, wide adaptability, easy to install. Combined needle roller bearings are widely used in machine tools, metallurgical machinery, textile machinery, printing machinery and other machinery and equipment, and make the mechanical system design is very compact and nimble.Aligning ball bearings Self-aligning ball bearings: two of the inner ring raceway and the raceway between the spherical outer ring, the assembly of the drum-shaped roller bearing. The outer ring raceway curvature center and bearing center line, and therefore have the same aligning and self-aligning ball bearings. Axis, the shell deflection occurs, you can automatically adjust to not increase the burden of bearing. Spherical roller bearings can bear radial load and axial load in two directions. Aligning ball bearing radial load capacity, suitable for a heavy impact loadconditions. The inner diameter is tapered bore bearings can be installed directly. Or use the adapter sleeve, remove the tube installed in the cylinder axis. Cage the use of steel stamping cage, forming polyamide-aligning ball bearings withstand heavy loads and impact loads, precision instruments, low noise motors, automobiles, motorcycles, metallurgy, mill, mining, petroleum, paper, cement, pressed sugar industry and the general machinery.Deep groove ball bearings imported bearings are mainly used for pure radial load, both radial and axial load. Only under pure radial load, the contact angle is zero. Performance of angular contact bearings, deep groove ball bearings with a larger radial clearance, and is subjected to high axial load. Deep groove ball bearings, the friction coefficient is small, the limit speed is also high, especially in a large high-speed operation of the axial load conditions, deep groove ball bearings Thrust ball bearings are more advantages. Deep groove ball bearings are the most representative of the rolling bearings, widely used. For high speed or high speed operation, and is very durable, without regular maintenance. The class has a small coefficient of friction, high limiting speed, simple structure, low manufacturing cost, easy to achieve high manufacturing precision. Size range and diversity, changes in the form used in precision instruments, low noise motors, automobiles, motorcycles and general machinery and other industries, is the machinery industry's most widely used type of bearings. The main radial load, and can withstand a certain amount of axial load deep groove ball bearings can be used for the transmission, instrumentation, motors, appliances, internal combustion engines, transportation vehicles, agricultural machinery, construction machinery, construction machinery and so on.Aligning roller bearing is a spherical outer ring between the two raceways of the inner ring raceway assembly with drum-shaped roller bearings. Aligning roller bearing with two rollers, mainly exposed to the diameter of a load, but also able to withstand the axial load in either direction. High radial load capacity, especially suitable for work overload or vibration loads, but can not afford the pure axial load. This kind of bearing outer ring raceway is spherical shape, aligning performance is good, can compensate concentricity error. Spherical roller bearings have two symmetrical spherical roller outer ring of a common spherical raceway, two bearing axis of inner ring tilt angle of the raceway, has a good aligning properties, when the axis force bearing when bending or install a different heart to continue its normal use, tune concentric with the bearing dimension series vary, generally allow aligning angle of 2.5 degrees, the type of loadbearing capacity, in addition to radial loads The outer bearings can withstand axial load of the two-way role, with good impact resistance, in general, self-aligning roller bearings allowed speed is low. Spherical roller bearings according to the section shape of the roller is divided into two different structures of the symmetrical spherical roller and non-symmetrical spherical roller, asymmetric self-aligning roller bearings are early products, mainly the host repair services, new design host rarely use symmetrical self-aligning roller bearings, the internal structure of the overall improvement of the design and parameters optimization, than with the early production of aligning roller bearings, able to withstand greater axial load, this bearing run lower temperatures, it can adapt to the requirements of high speed, according to whether the inner rib and cage can be divided into two kinds of C and CA, C-type bearing is characterized by the inner wall and the use of steel stamping frame, the CA-bearing characteristics for the inner ring on both sides have ribs machined solid cage in order to improve the lubrication, can provide users with the outer ring with a circular tank, and three hole Spherical roller bearings, set the code to the bearings / W33 can also supply according to the requirements of users with the inner hole of the aligning roller bearings, in order to facilitate customer handling and replacement of bearings, can also be provided within the hole with a taper aligning roller bearings, bearings, tapered bore, taper 1:12 after the set, code-named K, in order to adapt to specific user requirements can also be provided within the taper bearings of 1:30, followed by the set, code-named K30 hole with The taper of the bearing can be used locknut bearing mounted on the conical journal, but also can make use of the adapter sleeve or withdrawal sleeve bearings installed in the cylindrical journal.Combination of bearing: a bearing formed by the combination of bearing structure in the above-mentioned two or more of rolling bearings. Such as needle roller and cylindrical roller thrust bearings, needle roller and thrust ball bearings, needle roller and angular contact ball bearings, etc..Bearing life: under certain loads, the bearings in the number of revolutions or hours before pitting experienced, known as the bearing life.The life of rolling bearings of the number of revolutions (or number of hours worked under a certain speed) is defined: In this life within the bearing, any bearing ring or rolling body on the initial fatigue damage (spalling or defect). But both in the laboratory tests or in actual use, can clearly see the appearance of the same bearing in the same working conditions, to differ materiallyfrom actual life. In addition to the bearing of several different definitions of "life", one of the so-called "working life", it means that the actual life of a bearing can be achieved before the damage from the wear and tear, damage is usually not caused by fatigue, but caused by wear and tear, corrosion, seal damage.Due to differences in manufacturing precision, material uniformity, even if the same material, bearing the same batch of the same size, in the same working conditions, their longevity is not the same. In terms of statistical life is 1 unit relative life expectancy of up to four units, the shortest was 0.1 to 0.2 units, the ratio of the longest and shortest life of 20 to 40 times.The installation of bearings:Bearing installation, good or bad, will affect the accuracy, bearing life and performance. , The installation of the bearing, in accordance with the operating standards include the following items, including the bearing installation.①cleaning bearings and related parts have been greased bearings and bilateral withseals or dust cover, no need to clean before the installation of the ring bearing.② Check the size and finishing conditions of the relevant parts of the③installation method bearing installation should be based on the nature of the bearing structure, size, and bearing components with pressure should be directly added to a tight fit to the ferrule end surface, may not pass the pressure of the rolling element bearing installation generally use the following method: a press-fit bearing inner ring and shaft so tight fit, the outer ring and the bearing hole is loose with the available presses will be bearing the first pressure mounted on the shaft and the shaft together with the bearing with load bearing hole press-fit bearing inner ring side surface, pad assembly sleeve of a soft metal material (copper or mild steel), the assembly casing diameter should be slightly larger than the journal diameter, the diameter of the outer diameter than the bearing inner ring ribs slightly smaller, in order to avoid pressure in the cage. The bearing outer ring and the bearing hole is a tight fit, the inner ring and the shaft is loose with the bearing first pressed into the bearing hole, this time the assembly casing outside diameter should be slightly smaller than the diameter of the bore. If the bearing ring and shaft and housing bore are a tight fit to install the indoor ring and outer ring to be pressed into the shaft and housing bore, the assembly structure of the casing should be able to charge tight end face of the bearing inner and outer rings. (b) heating with heated bearings or bearing, the use of thermal expansionwill be a tight fit to change the installation method for a loose fit.④ bearing installation inspection⑤lubricant added to the installation of high-speed precision angular contact ball bearings, mainly for the load lighter, high-speed rotating occasions, the requirement of bearing high-precision, high speed, low temperature rise Low vibration and service life of high-speed precision angular contact ball bearings. Often for high-speed electric spindle bearing installed in pairs, the key component parts of the inner surface of the grinding machine of high speed electric spindle. The main technical indicators: 1. Bearing accuracy specifications: more than GB/307.1-94 the P4 level precision high-speed performance: dmN value of 1.3 ~ 1.8x 106 / min 3. Life (average):> 1500 hLife of high-speed precision angular contact ball bearings have a great relationship with the installation, you should note the following: ①The bearings shall be installed in a clean, clean room, bearing carefully matching, bearing spacers to go through grinding, maintaining the premise of high-inside and outside the ring spacers, spacer parallelism should be controlled in 1um following; ②The bearings prior to installation should be clean, cleaning inner slopes upward, should be flexible and feel no sense of stagnation, dried and put into the specified amount of grease, in the case of oil mist lubrication should be placed in a small amount of oil mist oil; ③bearing installation should be used specialized tools, even by force, strictly prohibited beating; ④The bearings shall be stored in clean air, corrosive gases, relative humidity of not more than 65 % long-term storage should be periodically rust-proof.Tapered roller bearings, water pump bearing installation:①the installation of bearings: bearing must be installed in a dry, clean environment conditions. Before installation, carefully check the mating surface of the shaft and shell, the face of the convex shoulder trench and connection quality of surface processing. All match the connected surface must be carefully cleaned and remove the burrs, casting raw surface must be in addition to net sand. Bearing installation should be preceded by cleaning with gasoline or kerosene, clean and dry before use, and to ensure good lubrication, bearings are commonly used grease lubrication, oil lubrication can be used. With grease lubrication should be used free of impurities, anti-oxidation, rust and extreme pressure performance superior grease. The grease filling is 30% to 60% of the bearings and the bearing capacity of the container, not too much. Withsealing structure of the double row tapered roller bearings and pump shaft bearing filled a good grease, users can directly use, not for cleaning. Bearing installation, you must exert equal pressure on the circumference of the ferrule end face pressed into the ring not want first-class tools to tap the bearing face, so as not to damage the bearing. Small amount of interference with the sleeve at room temperature, press and hold the bearing ring face hammer to beat the sleeve through the sleeve rings evenly pressed into. If large quantities of installation can be a hydraulic press.②bearing removal: Remove the bearing intend to continue to use, you should use the appropriate removal tool. The demolition of the interference fit of the ring, only to increase the tension in the ring, never to allow demolition of the rolling elements, or the rolling element and raceway will be crushed.③bearing use of the environment: the use of location and conditions of use and environmental conditions to select the specifications of size, accuracy, and with the right bearing is the premise to ensure that the bearing life and reliability. Parts: tapered roller bearings are suitable to withstand the radial load mainly radial and axial joint load, usually paired to two sets of bearings used primarily in the car's front and rear wheel hub, active bevel gear, differential, reducer and transmission parts. Allowable speed: correctly installed, well-oiled environment, allowing the bearing limit speed of 0.3 to 0.5 times. Under normal circumstances, the limit of 0.2 times the speed of the most suitable. Allow the angle of inclination: tapered roller bearings are generally not allowed axis of the relative shell hole tilt, where tilt maximum of not more than 2 '. Allow the temperature: under the normal load, the lubricant has high temperature resistance, and adequate lubrication conditions, the general bearing allows to work in -30 ° C to 150 ° C ambient temperature.Axis function and type:Axis is one of the important parts in the machine, used to support the rotating parts of machinery.Depending on the load bearing axis can be divided into the shaft, drive shaft and spindle three kinds. Shaft only transfer torque to withstand bending moments, such as the gear reducer shaft; drive shaft transmitting torque only not withstand the bending moment or bending moment is small. Such as automotive drive shaft; spindle is exposed only to the moment rather than transmit torque, such as the axis of the rail vehicle, the front axle of the bicycle.The shape of the shaft axis can be divided into: straight axle, crankshaft and flexible wire axis. Crankshaft is commonly used in reciprocating machinery. The flexible wire shaft wire layers close together by layers of flexible torque and rotational movement spread to any location commonly used in vibrators and other devices. This chapter only study the direct axis.Shaft design, manufacturing process according to job requirements and to consider other factors, the appropriate choice of materials, structural design, through strength and stiffness, set the axis of the structure shape and size, if necessary, consider the vibration stability.Axis of the commonly used materials:The axis of the material is often used carbon steel and alloy steel.Carbon steel bearing 35,45,50 high-quality carbon structural steel has higher mechanical properties, more applications, of which the most widely used steel 45. In order to improve its mechanical properties, normalizing or quenching and tempering treatment. Unimportant, or by a smaller force axis, can be used such as Q235, Q275 carbon structural steel.Alloy steel alloy steel has higher mechanical properties, but the price is more expensive, used for special requirements of the shaft. For example: the sliding bearings of high-speed shaft, commonly used in 20Cr, 20CrMnTi low-carbon alloy structural steel after carburizing can improve the wear resistance of the journal; generator rotor shaft in the high temperature, high-speed and overload conditions. must have good high temperature mechanical properties, often to adopt 40CrNi, 38CrMoAlA alloy structural steel. It is worth noting: the type and heat treatment of steel, its elastic modulus is very small. For use of alloy steel or heat treatment to improve the shaft stiffness is no practical results. In addition, the alloy steel higher sensitivity to stress concentration, alloy steel shaft design, more should be structured to avoid or reduce the stress concentration and reduce the surface roughness.Axis rough general round bar or forgings, and sometimes can be cast or ductile iron. For example, made of nodular cast iron crankshaft, camshaft, low cost, better vibration absorption, low sensitivity to stress concentration, good strength, etc..Axis of structural design:The axis of the structure design is to make each part of the axis has a reasonable shape and size. Its main requirements are: 1) axis should be easy processing. Parts of the shaft to be easy disassembly (manufacture and installation requirements); 2) axis and the shaft parts have accurateposition (location); 3) parts to firmly and reliably and relatively fixed (fixed); 4) to improve the force situation, reducing the stress concentration.①The manufacturing installation requirementsIn order to facilitate the assembly and disassembly of the shaft parts, often the shaft made of the ladder. Split the box in the shaft, its diameter from the shaft end and gradually increases toward the middle. As shown above, can turn the gear, the sleeve, the left end bearings, bearing caps and pulley from the axis of the left end assembly and disassembly, and another from the right end of the assembly and disassembly of rolling bearings. Shaft parts is easy to install, should chamfer of the shaft end and the end of the shaft section.Axis grinding shaft section should wheel the more process slots; car threaded shaft section should be undercut.Meet the requirements of the case, the axis of the shape and size should be simple in order to facilitate processing.②The axis positioning of partsLadder shaft cross-section changes a place called the shaft shoulder, since the axial positioning of the role. Shaft shoulder makes gear positioned on the shaft; shaft shoulder pulley positioning; shaft shoulder to the right end of the rolling bearing positioning.Some parts rely on a set of simple positioning, such as above the left end of rolling bearings.③The axis parts of the fixedAxial fixation of the shaft parts, often with the shaft shoulder, sleeve, nut or shaft end of the retaining ring (also known as the plate) and other forms. Gear to achieve the axial two-way fixed. Gear by the axial force, right through the shaft shoulder, by the axis and shoulders in the rolling bearing inner ring; left sleeve top in the rolling bearing inner ring. Can not use the sleeve or sleeves too long, we can use the round nut to be fixed. Pulley axial fixed retaining ring depend on the shaft shoulder and the shaft end.Axis intensity calculated as follows:Axis intensity shall be calculated according to the shaft bearing, using the appropriate method of calculation. The common axis strength calculation method has the following two:① Press the torsional strength calculationThis method applies only to withstand the torque of the drive shaft of accurate calculation, iswell received by the bending moment and torque axis approximate calculation can also be used. Circular section shaft transmitting torque only, the strength condition.Withstand both pass to turn short axis of the bending moment can also be used on the preliminary estimate of the diameter of the design formula:In addition, the empirical formula can be used to estimate the diameter of the shaft. For example, in the general reducer, high-speed input shaft diameter according to its associated motor shaft diameter D estimates, d = (0.8 ~ 1. 2) D; all levels of low-speed shaft of the gear center distance on the shaft diameter according to the same level a estimates, d = (0.3 0.4) a.② According to the synthetic strength of the bending and torsionSingle-stage cylindrical gear reducer design sketches, each symbol indicates the length of the Dimensions. Obviously, when the parts laid out on the sketch, the role of location of the external load and support reaction force can be determined. Thus can be used for mechanical analysis of the shaft and draw the bending moment diagram and torque diagram. Then you can press the synthetic strength of the bending and torsion shaft diameter.For the cross-section of the keyway should be calculated shaft diameter increased by about 4%. Calculated shaft diameter greater than the shaft diameter of preliminary estimates of the structural design, that the strength of the chart axis is not enough, you must modify the structural design; calculated shaft diameter less than the estimates of the structural design of shaft diameter, and the difference is not very generally subject to the structural design of the shaft diameter.For general-purpose shaft designed by the above method can. Important axis, yet further strength check (such as the safety factor method), the calculation method available at the reference.Shaft stiffness calculated as follows:Axis by the bending moment will produce a bending torque role will have the torsional deformation. If the shaft stiffness is not enough, it will affect the normal work of the axis. For example, the deflection of the rotor shaft is too large, will change the rotor and stator gap and affect the performance of the motor. Another example is the rigidity of the machine spindle is enough, it will affect the machining accuracy. Therefore, in order so that the axis is not enough stiffness and failure, must be designed to limit their working conditions under the shaft deformationAxis of the concept of critical speed:Uneven due to structural asymmetries of the rotary parts, materials, processing errors and other reasons, to make the rotation center of gravity is precisely located in the geometric axis, it is almost impossible. In fact, the center of gravity and the geometric axis generally total a slight eccentricity, and thus the centrifugal force generated when rotating the axis by the interference of cyclical loading.Axis suffered external frequency axis since the vibration frequency of the same operation will be unstable vibration occurs, a phenomenon known as the resonance of the shaft. Resonance when the shaft speed is called the critical speed. If the shaft speed is stuck near the critical speed, the axis of deformation increases rapidly, as well as the axis, the extent of the damage or even the whole machine. Therefore, the important, especially high-speed axis to calculate the critical speed, and shaft speed n to avoid the critical speed nc.The shaft critical speed, the lowest one called the first critical speed, the remaining second, third ......Speed is below a first critical speed axis is called the rigid shaft; more than the first critical speed axis is called the flexible shaft.Slender axis machining process characteristics:(1) slender shaft turning the process characteristicsSlender shaft rigidity is poor, turning fashion folder properly, it is easy because of the role of cutting force and gravity bending deformation,Vibration, thus affecting the machining accuracy and surface roughness.The slender shaft of the thermal diffusivity of poor performance, the effect of cutting heat, will produce quite a large linear expansion. If the two ends of the shaft to a fixed support, the workpiece due to the elongation of the top bend.The longer axis, a walk the knife for a long time, tool wear, thus affecting the geometry of the precision of the parts.Car slender shaft supporting the workpiece with the tool holder, the two supporting block inappropriate parts pressure will affect the machining accuracy. If the pressure is too small or do not touch, it does not work, you can not improve the stiffness of the parts; if the pressure is too large, the parts are pressed to the lathe tool, the cutting depth increases, the car out of the diameter is small, continue to move with the turret bearing block support in the small-diameter cylindrical。