机械类外文翻译译文轴和齿轮的设计及应用

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机械零件齿轮中英文对照外文翻译文献

(文档含英文原文和中文翻译)中英文资料对照外文翻译Machine Parts (I)GearsGears are direct contact bodies, operating in pairs, that transmit motion and force from one rotating shaft to another or from a shaft to a slide (rack), by means of successively engaging projections called teeth.Tooth profiles. The contacting surfaces of gear teeth must be aligned in such a way that the drive is positive; i.e., the load transmitted must not depend on frictional contact. As shown in the treatment of direct contact bodies, this requires that thecommon normal to the surfaces not to pass through the pivotal axis of either the driver or the follower.As it is known as direct contact bodies, cycloidal and involute profiles profiles provide both a positive drive and a uniform velocity ratio;i.e., conjugate action.Basic relations. The smaller of a gear pair is called the pinion and the larger is the gear. When the pinion is on the driving shaft the pair is called the pinion and the larger is the gear. When the pinion is on the driving shaft the pair acts as a speed reducer; When the gear drives, the pair is a speed incrreaser. Gears are more frequently used to reduce speed than to increase it.If a gear having N teeth rotates at n revolutions per minute, the product N*n has the dimension “teeth per minute”. This product must be the same for both members of a mating pair if each tooth acquires a partner from the mating gear as it passes through the region of tooth engagement.For conjugate gears of all types, the gear ratio and the speed ratio are both given by the ratio of the number of teeth on the gear to the number of teeth on the pinion. If a gear has 100 teeth and a mating pinion has 20, the ratio is 100/20=5. Thus the pinion rotates five times as fast as the gear, regardless of the gear. Their point of tangency is called the pitch point, and since it lies on the line of centers, it is the only point at which the profiles have pure roling contact. Gears on nonparallel, non-intersecting shafts also have pitch circles, but the rolling-pitch –circle concept is not valid.Gear types are determined largely by the disposition of the shafts; in addition, certain types are better suited than others for large speed changes. This means that if a specific disposition of the shafts is required, the type of gear will more or less be fixed. On the other hand, if a required speed change demands a certain type, the shaft positions will also be fixed.Spur gears and helical gears. A gear having tooth elements that are straight and parallel to its axis is known as a spur gear. A spur pair can be used to connect parallel shafts only.If an involute spur pinion were made of rubber and twisted uniformly so that the ends rotated about the axis relative to one another, the elements of the teeth, initially straight and parallel to the axis, would become helices. The pinion then in effect would become a helical gear.Worm and bevel gears. In order to achieve line contact and improve the load carrying capacity of the crossed axis helical gears, the gear can be made to curvepartially around the pinion, in somewhat the same way that a nut envelops a screw. The result would be a cylindrical worm and gear. Worms are also made in the shape of an hourglass, instead of cylindrical, so that they partially envelop the gear. This results in a further increase in load-carrying capacity.Worm gears provide the simplest means of obtaining large ratios in a single pair. They are usually less efficient than parallel-shaft gears, however, because of an additional sliding movement along the teeth.V-beltThe rayon and rubber V-belt are widely used for power transmission. Such belts are made in two series: the standard V-belt and the high capacity V-belt. The belts can be used with short center distances and are made endless so that difficulty with splicing devices is avoided.First, cost is low, and power output may be increased by operating several belts side by side. All belts in the drive should stretch at the same rate in order to keep the load equally divided among them. When one of the belts breaks, the group must usually be replaced. The drive may be inclined at any angle with tight side either top or bottom. Since belts can operate on relatively small pulleys, large reductions of speed in a single drive are possible.Second，the included angle for the belt groove is usually from 34°to 38°.The wedging action of the belt in the groove gives a large increase in the tractive force developed by the belt.Third，pulley may be made of cast iron, sheet steel, or die-cast metal. Sufficient clearance must be provided at the bottom of the groove to prevent the belt from bottoming as it becomes narrower from wear. Sometimes the larger pulley is not grooved when it is possible to develop the required tractive force by running on the inner surface of the belt. The cost of cutting the grooves is thereby eliminated. Pulleys are on the market that permit an adjustment in the width of the groove. The effective pitch diameter of the pulley is thus varied, and moderate changes in the speed ratio can be secured.Chain DrivesThe first chain-driven or “safety” bicycle appeared in 1874, and chains were used for driving the rear wheels on early automobiles. Today, as the result of modern design and production methods, chain drives that are much superior to their prototypes are available, and these have contributed greatly to thedevelopment of efficient agricultural machinery, well-drilling equipment, and mining and construction machinery. Since about 1930 chain drives have become increasingly popular, especially for power saws, motorcycle, and escalators etc.There are at least six types of power-transmission chains; three of these will be covered in this article, namely the roller chain, the inverted tooth, or silent chain, and the bead chain. The essential elements in a roller-chain drive are a chain with side plates, pins, bushings (sleeves), and rollers, and two or more sprocket wheels with teeth that look like gear teeth. Roller chains are assembled from pin links and roller links. A pin link consists of two side plates connected by two pins inserted into holes in the side plates. The pins fit tightly into the holes, forming what is known as a press fit. A roller link consists of two side plates connected by two press-fitted bushings, on which two hardened steel rollers are free to rotate. When assembled, the pins are a free fit in the bushings and rotate slightly, relative to the bushings when the chain goes on and leaves a sprocket.Standard roller chains are available in single strands or in multiple strands, In the latter type, two or more chains are joined by common pins that keep the rollers in the separate strands in proper alignment. The speed ratio for a single drive should be limited to about 10∶1; the preferred shaft center distance is from 30 to 35 times the distance between the rollers and chain speeds greater than about 2500 feet (800 meters) per minute are not recommended. Where several parallel shafts are to be driven without slip from a single shaft, roller chains are particularly well suited.An inverted tooth, or silent chain is essentially an assemblage of gear racks, each with two teeth, pivotally connected to form a closed chain with the teeth on the inside, and meshing with conjugate teeth on the sprocket wheels. The links are pin-connected flat steel plates usually having straight-sided teeth with an included angle of 60 degrees. As many links are necessary to transmit the power and are connected side by side. Compared with roller-chain drives, silent-chain drives are quieter, operate successfully at higher speeds, and can transmit more load for the same width. Some automobiles have silent-chain camshaft drives.Bead chains provide an inexpensive and versatile means for connecting parallel or nonparallel shafts when the speed and power transmitted are low. The sprocket wheels contain hemispherical or conical recesses into which the beads fit. The chains look like key chains and are available in plain carbon and stainless steel and also in the form of solid plastic beads molded on a cord. Bead chains are used oncomputers, air conditioners, television tuners, and Venetian blinds. The sprockets may be steel, die-cast zinc or aluminum, or molded nylon.Machine Parts (II)FastenerFasteners are devices which permit one part to be joined to a second part and, hence, they are involved in almost all designs.There are three main classifications of fasteners, which are described as follows：(1) Removable. This type permits the parts to be readily disconnected without damaging the fastener. An example is the ordinary nut-and-bolt fastener.(2) Semi permanent. For this type, the parts can be disconnected, but some damage usually occurs to the fastener. One such example is a cotter pin.(3) Permanent. When this type of fastener is used, it is intended that the parts will never be disassembled. Examples are riveted joints and welded joints.The importance of fasteners can be realized when referring to any complex product. In the case of the automobile, there are literally thousands of parts which are fastened together to produce the total product. The failure or loosening of a single fastener could result in a simple nuisance such as a door rattle or in a serious situation such as a wheel coming off. Such possibilities must be taken into account in the selection of the type of fastener for the specific application.Nuts, bolts, and screws are undoubtedly the most common means of joining materials. Since they are so widely used, it is essential that these fasteners attain maximum effectiveness at the lowest possible cost. Bolts are, in reality, carefully engineered products with a practically infinite use over a wide range of services.An ordinary nut loosens when the forces of vibration overcome those of friction. In a nut and lock washer combination, the lock washer supplies an independent locking feature preventing the nut from loosening. The lock washer is useful only when the bolt might loosen because of a relative change between the length of the bolt and the parts assembled by it. This change in the length of the bolt can be caused by a number of factors-creep in the bolt, loss of resilience, difference in thermal expansion between the bolt and the bolted members, or wear. In the above static cases, the expanding lock washer holds the nut under axial load and keeps the assembly tight. When relative changes are caused by vibration forces, the lock washer is not nearly as effective.Rivets are permanent fasteners. They depend on deformation of their structure for their holding action. Rivets are usually stronger than the thread-type fastener and are more economical on a first-cost basis. Rivets are driven either hot or cold,depending upon the mechanical properties of the rivet material. Aluminum rivets, for instance, are cold-driven, since cold working improves the strength of aluminum. Most large rivets are hot-driven, however.ShaftVirtually all machines contain shafts. The most common shape for shafts is circular and the cross section can be either solid or hollow (hollow shafts can result in weight savings).Shafts are mounted in bearings and transmit power through such devices as gears, pulleys, cams and clutches. These devices introduce forces which attempt to bend the shaft; hence, the shaft must be rigid enough to prevent overloading of the supporting bearings. In general, the bending deflection of a shaft should not exceed 0.01 in. per ft. of length between bearing supports.For diameters less than 3 in., the usual shaft material is cold-rolled steel containing about 0.4 percent carbon. Shafts are either cold-rolled or forged in sizes from 3 in. to 5 in. .For sizes above 5 in. , shafts are forged and machined to size. Plastic shafts are widely used for light load applications. One advantage of using plastic is safety in electrical applications, since plastic is a poor conductor of electricity.Another important aspect of shaft design is the method of directly connecting one shaft to another. This is accomplished by devices such as rigid and flexible couplings.BearingA bearing can be defined as a member specifically designed to support moving machine components. The most common bearing application is the support of a rotating shaft that is transmitting power from one location to another. Since there is always relative motion between a bearing and its mating surface, friction is involved. In many instances, such as the design of pulleys, brakes, and clutches, friction is desirable. However, in the case of bearings, the reduction of friction is one of the prime considerations：Friction results in loss of power, the generation of heat, and increased wear of mating surfaces.The concern of a machine designer with ball bearings and roller bearings is fivefold as follows：(1) Life in relation to load; (2) stiffness, i.e. deflections under load;(3) friction; (4) wear; (5) noise. For moderate loads and speeds the correct selection ofa standard bearing on the basis of load rating will usually secure satisfactoryperformance. The deflection of the bearing elements will become important where loads are high, although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard to the hostility of the environment.Notwithstanding the fact that responsibility for the basic design of ball bearings and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by abutting against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to allow space for this.A journal bearing, in its simplest form, is a cylindrical bushing made of a suitable material and containing properly machined inside and outside diameters. The journal is usually the part of a shaft or pin that rotates inside the bearing.Journal bearings operate with sliding contact, to reduce the problems associated with sliding friction in journal bearings, a lubricant is used in conjunction with compatible mating materials. When selecting the lubricant and mating materials, one must take into account bearing pressures, temperatures and also rubbing velocities. The principle function of the lubricant in sliding contact bearings is to prevent physical contact between the rubbing surfaces. Thus the maintenance of an oil film under varying loads, speeds and temperature is the prime consideration in sliding contact bearings.Introduction to Machinery DesignMachinery design is either to formulate an engineering plan for the satisfaction of a specified need or to solve an engineering problem. It involves a range of disciplines in materials, mechanics, heat, flow, control, electronics and production.Machinery design may be simple or enormously complex, easy or difficult, mathematical or nonmathematical, it may involve a trivial problem or one of great importance. Good design is the orderly and interesting arrangement of an idea to provide certain results or effects. A well-designed product is functional, efficient, and dependable. Such a product is less expensive than a similar poorly designed product that does not function properly and must constantly be repaired.People who perform the various functions of machinery design are typically called industrial designers. He or she must first carefully define the problem, using an engineering approach, to ensure that any proposed solution will solve the right problem. It is important that the designer begins by identifying exactly how he or she will recognize a satisfactory alternative, and how to distinguish between two satisfactory alternatives in order to identify the better. So industrial designers must have creative imagination, knowledge of engineering, production techniques, tools, machines, and materials to design a new product for manufacture, or to improve an existing product.In the modern industrialized world, the wealth and living standards of a nation are closely linked with their capabilities to design and manufacture engineering products. It can be claimed that the advancement of machinery design and manufacturing can remarkably promote the overall level of a country’s industrization. Our country is playing a more and more vital role in the global manufacturing industry. To accelerate such an industrializing process, highly skilled design engineers having extensive knowledge and expertises are needed.Machinery ComponentsThe major part of a machine is the mechanical system. And the mechanical system is decomposed into mechanisms, which can be further decomposed into mechanical components. In this sense, the mechanical components are the fundamental elements of machinery. On the whole, mechanical components can be classified as universal and special components. Bolts, gear, and chains are the typical examples of the universal components, which can be used extensively in different machines across various industrial sectors. Turbine blades, crankshaft and aircraftpropeller are the examples of the special components, which are designed for some specific purposes.Mechanical Design ProcessProduct design requires much research and development. Many concepts of an idea must be studied, tried, refined, and then either used or discarded. Although the content of each engineering problem is unique, the designers follow the similar process to solve the problems.Recognition of NeedSometimes, design begins when a designer recognizes a need and decides to do something about it. The need is often not evident at, all; recognition is usually triggered by a particular adverse circumstance or a set of random circumstances, which arise almost simultaneously. Identification of need usually consists of an undefined and vague problem statement.Definition of ProblemDefinition of problem is necessary to fully define and understand the problem, after which it is possible to restate the goal in a more reasonable and realistic way than the original problem statement. Definition of the problem must include all the specifications for the thing that is to be designed. Obvious items in the specifications are the speeds, feeds, temperature limitations, maximum range, expected variation in the variables, and dimensional and weight limitations.SynthesisThe synthesis is one in which as many alternative possible design approaches are sought, usually without regard for their value or quality. This is also sometimes called the ideation and invention step in which the largest possible number of creative solutions is generated. The synthesis activity includes the specification of material, addition of geometric features, and inclusion of greater dimensional detail to the aggregate design.AnalysisAnalysis is a method of determining or describing the nature of something by separating it into its parts. In the process the elements, or nature of the design, are analyzed to determine the fit between the proposed design and the original design goals.EvaluationEvaluation is the final proof of a successful design and usually involves thetesting of a prototype in the laboratory. Here we wish to discover if the design really satisfies the needs.The above description may give an erroneous impression that this process can be accomplished in a linear fashion as listed. On the contrary, iteration is required within the entire process, moving from any step back to any previous step, in all possible combinations, and doing this repeatedly.PresentationCommunicating the design to others is the finial, vital presentation step in the design process. Basically, there are only three means of communication. These are the written, the oral, and the graphical forms. A successful engineer will be technically competent and versatile in all three forms of communication. The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, the greatest gains are obtained by those willing to risk defeat.Contents of Machinery DesignMachinery design is an important technological basic course in mechanical engineering education. Its objective is to provide the concepts, procedures, data, and decision analysis techniques necessary to design machine elements commonly found in mechanical devices and systems; to develop engineering students’ competence of machine design that is the primary concern of machinery manufacturing and the key to manufacture good products.Machinery design covers the following contents：Provides an introduction to the design process, problem formulation, safety factors.Reviews the material properties and static and dynamic loading analysis, including beam, vibration and impact loading.Reviews the fundamentals of stress and defection analysis.Introduces static failure theories and fracture-mechanics analysis for static loads.Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in the design of rotation machinery.Discusses thoroughly the phenomena of wear mechanisms, surface contact stresses, and surface fatigue.Investigates shaft design using the fatigue-analysis techniques.Discusses fluid-film and rolling-element bearing theory and application.Gives a thorough introduction to the kinematics, design and stress analysis of spur gears, and a simple introduction to helical, bevel, and worm gearing.Discusses spring design including helical compression, extension and torsion springs.Deals with screws and fasteners including power screw and preload fasteners.Introduces the design and specification of disk and drum clutches and brakes.机械零件(I)齿轮齿轮是直接接触，成对工作的实体，在称为齿的凸出物的连续啮合作用下，齿轮能将运动和力从一个旋转轴传递到另一个旋转轴，或从一个轴传递到一个滑块(齿条)。

机械工程及自动化专业外文翻译--齿轮的特点和作用

外文原文：Gear features and functionsAbstractGears in the mechanical equipment to achieve an integral, it is a lot of superior performance. The appropriate gear and reasonable use of transmission gears can improve equipment performance but also could prolong gear life.KeywordsGear, characteristics, fault, applicationWheel gear's spreading to move is a the most wide kind of the application spreads to move a form in the modern machine.Its main advantage BE1 spreads to move to settle, work than in a moment steady, spread to move accurate credibility, can deliver space arbitrarily sport and the motive of the of two stalks；Power and speed scope2 applies are wide；3 spreads to move an efficiency high, η =0.92-0.98；4 work is dependable, service life long；5 Outline size outside the is small, structure tightly packed.The wheel gear constituted to°；；；from wheel gear, stalk, bearings and box body decelerates a machine, useding for prime mover and work machine or performance organization of, have already matched to turn soon and deliver a function of turning , the application is extremely extensive in the modern machine.6 Local deceleration machine much with the wheel gear spread to move, the pole spread to move for lord, but widespread exist power and weightratio small, or spread to move ratio big but the machine efficiency leada low problem.There are also many weaknesses on material quality and craftlevel moreover, the especially large deceleration machine's problem ismore outstanding, the service life isn't long.The deceleration machineof abroad, with Germany, Denmark and Japan be placed in to lead a position,occupying advantage in the material and the manufacturing craft specially,decelerating the machine work credibility like, service life long.But itspreads to move a form to still take settling stalk wheel gear to spreadto move as lord, physical volume and weight problem, don't also resolvelike The direction which decelerates a machine to is the facing big powerand spread to move ratio, small physical volume, high machine efficiencyand service life to grow greatly nowadays develops.Decelerating theconnecting of machine and electric motor body structure is also the formwhich expands strongly, and have already produced various structure formsand various products of power model numbers.Be close to ten several inthe last yearses, control a technical development because of the moderncalculator technique and the number, make the machine process accuracy,process an efficiency to raise consumedly, pushed a machine to spread thediversification of movable property article thus, the mold piece of thewhole machine kit turns, standardizing, and shape design the art turn,making product more fine, the beauty turns. Become a set a machine material In 21 centuries medium, the wheel gear is still a machine to spreada dynamic basic C tool machine and the craft technical development,pushed a machine to spread to move structure to fly to develop soon.Bespreading to move the electronics control, liquid in the system designto press to spread to move, wheel gear, take the mixture of chain to spreadto move, will become become soon a box to design in excellent turn to spreadto move a combination of direction.The academics that is in spread movethe design crosses, will become new spread a movable property article theimportant trend of the development. Is the use of gear teeth of two gears meshing each other transmission of mechanical power and motion transmission. According to the relative position of the gear axis parallel to axis of cylindrical sub-gear drive, bevel gear axis intersect and cross-axis helical drive gear. Compact structure, high efficiency, long life and so on. Gear refers to the main, driven wheel gear direct, movement and power transmission devices. Of all the mechanical transmission, the most widely used gear can be used to transfer between any two axes of motion and power.The characteristics of gear is: a smooth gear transmission, the transmission ratio accurate, reliable, high efficiency, long life, the use of power, speed and size range. For example, transmission of power from small to almost 100,000 kilowatts; speeds of up to 300m / s; gear diameter from a few millimeters to more than 20 meters. However, the need for specialized gear manufacturing equipment, the meshing noise transmission. Gear failure for the five forms, should be the appropriate design criteria established. However, tooth wear, plastic deformation and so on, as they have not been widely established and well-established engineering practice to use the calculation method and design data, so the gear drive design, it is usually only on the guarantee that the tooth root bending fatigue strength and tooth surface to ensure contact fatigue strength calculation of the two criteria. For high-power high-speed gear transmission (such as aero-engine main drive, drive turbine-generator unit, etc.), but also ensure the tooth surface by the anti-bonding capacity calculation guidelines. As for the ability to resist other failure, although generally not at present be calculated, but the measures to be taken to strengthen the tooth's ability to resist these failures.1 closed gear transmission Informed by practice, in the closed gear transmission, usually to ensure that the main tooth contact fatiguestrength. Tooth surface hardness for high strength and low core-tooth gear (such as 20,20 Cr steel by quenching after carburizing gears) or a more brittle material of the gear, usually at the tooth root bending fatigue strength to ensure that the main. If the two gears are hardened and the tooth surface hardness as high as, then as the case may be. Larger transmission power, such as the input power of 75kW closed more than gear, heat, easy to lead to bad lubrication and gear damage, such as glue, in order to control the temperature rise, but also for calculation of cooling capacity.2 open-gear transmission Open (semi-open) gear drive, according to tooth surface is supposed to be based to ensure that anti-wear and anti-fracture ability Dedendum two criteria are calculated, but as mentioned earlier, on the tooth surface abrasion resistance of the method of calculating capacity is not perfect yet, so off-type (semi-open) gear drive, the current only to ensure that the tooth root bending fatigue strength as a design criteria. In order to extend the open (semi-open) the life of gear, the specific needs of visualization to be obtained by increasing the appropriate modulus. Reducer is the prime mover with an independent closed between the work gear to reduce speed and to increase torque. In addition, in some occasions, there are devices used for growth, and known as the accelerator. When the motor output shaft speed input from the initiative, the drive pinion rotation, and the drive pinion gear movement, and a large number of teeth than the gear pinion, and the speed ratio gear pinion slow, then the shaft gear ( output shaft) output, which has played the role of output slowdown. Reducer of the type, variety, many types have been formulated for the trip (the country) the subject of more than 40 kinds of reducer. Reducer is based on the type of gear used, tooth profile curve divided; reducer species is based on the use of the different needs of the reducer structure; the type of reducer in the basic structure ofthe tooth surface, based on hardness, transmission level, the shaft type, assembly type, installation type, connection type and other factors designed reducer different characteristics. Reducer connected with the work load of the state of more complex machines, a great impact on the speed reducer is a reducer selection and calculation of an important factor in the load reducer that is the work of the state machine (from the motives) of the load, and is usually divided into three categories: 1 uniform load;2 Medium impact load; 3 strong impact load. Mechanical aspects of the slowdown in the devices typically are:1 for the speed is relatively small, less torque on the gear drive system - ranging from a pair of gear teeth (speed) or a range of gear teeth ( variable speed). Large number of teeth for which the driving wheel, a large number of teeth used for the driven wheel.2 for speed is relatively small, a larger torque on the gear drive system - a screw and a gear. Screw driving force with which to make decisions. If the gear teeth for N, while rotating around each gear, screw on the ring must be rotating N.3 for the speed ratio, and torque transmission on a large turbine vice - a rod and a vortex turbine. Used to decide under which vortex dynamics. If the turbine for the number of teeth N, while rotating around each turbine, vortex must be rotating N pole lap. Air power plant is typically used for turbine Vice reducer.Its role is to:1 deceleration at the same time increase the output torque, torque output by motor output by the ratio of reduction ratio, but bearing in mind that do not exceed the rated torque reducer.2 The speed at the same time reducing the load inertia, the reduction of inertia than the square of speed. We can look at General Electric has a value of inertia. There is a general helical gear reducer reducer(including parallel shaft helical gear reducer, worm gear reducer, bevel gear reducer, etc.), planetary gear reducer, cycloid reducer, worm gear reducer, planetary-type friction mechanical CVT machine and so on. And we have a common type of speed reducer:1 worm gear reducer is a main feature of the reverse self-locking function, can have a larger reduction ratio, input shaft and output shaft axis is not the same, nor in the same plane . But in general larger, the transmission efficiency is not high, the accuracy is not high.2 harmonic of the harmonic drive speed reducer is to use flexible components of the elastic deformation controlled to convey movement and momentum, and volume not very high accuracy, but the drawback is the limited life Flexspline, the impact of intolerance, rigidity and metal pieces compared to poor.3 planetary reducer compare the advantage of compact structure, the return gap small, high precision, long life, rated output torque can do a lot. Enter the speed can not be too high. However, the price a little expensive. Mechanical transmission is the use of mechanical power transmission and motion transmission. Mechanical transmission in mechanical engineering in a wide range of applications, there are a variety of forms, can be divided into two categories1 by mechanical friction between the transmission of power and movement of the friction drive, including belt drive, rope drive and friction wheel drive and so on. Easy to achieve continuously variable friction transmission, and most of them can adapt to the larger axis of the transmission distance of occasions, been able to play a buffer containing the spin and the role of the protection gear, but generally can not be used for high-power transmission of the occasion, there is no guarantee that an accurate the transmission ratio.2 items by active engagement with the follower, or through transmissionof power or middleware meshing engagement campaign drive, including the gear drive, chain drive, screw drive and harmonic drive and so on. Meshing can be used for high-power transmission of the occasions, the exact transmission ratio, but the general requirements for the manufacture of high precision and accuracy of the installation. The form of mechanical transmission is divided into: friction drive, chain drive, gear drive, belt drive, under vortex turbine drive, ratchet drive, the crankshaft connecting rod drive, pneumatic drive, hydraulic transmission (hydraulic plane), universal joint transmission,steel transmission (the most widely elevator) drive coupling, spline drive.中文译文：齿轮的特点和作用摘要齿轮实现在机械设备中不可缺少的组成，它很多优越的性能。

轴和齿轮的设计及应用外文翻译、中英文翻译、外文文献翻译

英文原文：SHAFT AND GEAR DESIGNAbstract: The important position of the wheel gear and shaft can' t falter in traditional machine and modern machines. The wheel gear and shafts mainly install the direction that delivers the dint at the principal axis box. The passing to process to make them can is divided into many model numbers, useding for many situations respectively. So we must be the multilayers to the understanding of the wheel gear and shaft in many waysKey words : Wheel gear ; ShaftIn the force analysis of spur gears, the forces are assumed to act in a single plane .We shall study gears in which the forces have three dimensions.The reason for this, in the case of helical gears, is that the teeth are not parallel to the axis of rotation. And in the case of bevel gears, the rotational axes are not parallel to each other. There are also other reasons, as we shall learn.Helical gears are used to transmit motion between parallel shafts. The helix angle is the same on each gear, but one gear must have a right-hand helix and the other a left-hand helix. The shape of the tooth is an involute helicoid. If a piece of paper cut in the shape of a parallelogram is wrapped around a cylinder, the angular edge of the paper becomes a helix. If we unwind this paper, each point on the angular edge generates an involute curve. The surface obtained when every point on the edge generates an involute is called an involute helicoid. The initial contact of spur-gear teeth is a line extending all the way across the face of the tooth. The initial contact of helical gear teeth is a point, which changes into a line as the teeth come into more engagement. In spur gears the line of contact is parallel to the axis of the rotation; in helical gears, the line is diagonal across the face of the tooth. It is this gradual of the teeth and the smooth transfer of load from one tooth to another, which give helical gears the ability to transmit heavy loads at high speeds. Helical gears subject the shaft bearings to both radial and thrust loads. When the thrust loads become high or are objectionable for other reasons, it may be desirable to use double helical gears. A double helical gear (herringbone) is equivalent to two helical gears of opposite hand, mounted side byside on the same shaft. They develop opposite thrust reactions and thus cancel out the thrust load. When two or more single helical gears are mounted on the same shaft,the hand of the gears should be selected so as to produce the minimum thrust load Crossed-helical, or spiral, gears are those in which the shaft centerlines are neither parallel nor intersecting. The teeth of crossed-helical fears have point contact with each other, which changes to line contact as the gears wear in. For this reason they will carry out very small loads and are mainly for instrumental applications, and are definitely not recommended for use in the transmission of power There is on difference between a crossed heli cal gear and a helical gear until they are mounted in mesh with each other. They are manufactured in the same way. A pair of meshed crossed helical gears usually have the same hand; that is , a right-hand driver goes with a right-hand driven. In the design of crossed-helical gears, the minimum sliding velocity is obtained when the helix angle are equal. However, when the helix angle are not equal, the gear with the larger helix angle should be used as the driver if both gears have the same handWorm gears are similar to crossed helical gears. The pinion or worm has a small number of teeth, usually one to four, and since they completely wrap around the pitch cylinder they are called threads. Its mating gear is called a worm gear, which is not a true helical gear. A worm and wormgear are used to provide a high angular-velocity reduction between nonintersecting shafts which are usually at right angle. The worm gear is not a helical gear because its face is made concave to fit the curvature of the worm in order to provide line contact instead of point contact. However, a disadvantage of worm gearing is the high sliding velocities across the teeth, the same as with crossed helical gearsWorm gearing are either single or double enveloping. A single-enveloping gearing is one in which the gear wraps around or partially encloses the worm. . A gearing in which each element partially encloses the other is, of course, a double-enveloping worm gearing. The important difference between the two is that area contact exists between the teeth of doubleenveloping gears while only line contact between those of single-enveloping gears. The worm and worm gear of a set have the same hand ofhelix as for crossed helical gears, but the helix angles are usually quite different The helix angle on the worm is generally quite large, and that on the gear very small Because of this, it is usual to specify the lead angle on the worm, which is the complement of the worm helix angle, and the helix angle on the gear; the two angles are equal for a 90-deg. Shaft angleWhen gears are to be used to transmit motion between intersecting shaft, some of bevel gear is required. Although bevel gear are usually made for a shaft angle of 90 deg. They may be produced for almost any shaft angle. The teeth may be cast, milled, or generated. Only the generated teeth may be classed as accurate. In a typical bevel gear mounting, one of the gear is often mounted outboard of the bearing. This means that shaft deflection can be more pronounced and have a greater effect on the contact of teeth. Another difficulty, which occurs in predicting the stress in bevel-gear teeth, is the fact the teeth are tapered.Straight bevel gears are easy to design and simple to manufacture and give very good results in service if they are mounted accurately and positively. As in the case of squr gears, however, they become noisy at higher values of the pitch-line velocity In these cases it is often go od design practice to go to the spiral bevel gear, which is the bevel counterpart of the helical gear. As in the case of helical gears, spiral bevel gears give a much smoother tooth action than straight bevel gears, and hence are useful where high speed are encountered. It is frequently desirable, as in the case of automotive differential applications, to have gearing similar to bevel gears but with the shaft offset. Such gears are called hypoid gears because their pitch surfaces are hyperboloids of revolution The tooth action between such gears is a combination of rolling and sliding alonga straight line and has much in common with that of worm gears A shaft is a rotating or stationary member, usually of circular cross section, having mounted upon it such elementsas gears, pulleys, flywheels, cranks, sprockets, and other power-transmission elements. Shaft may be subjected to bending, tension, compression, or torsional loads, acting singly or in combination with one another. When they are combined, one may expect to find both static and fatigue strength tobe important design considerations, since a single shaft may be subjected to static stresses, completely reversed, and repeated stresses, all acting at the same time The word "shaft" covers numerous variations, such as axles and spindles. Anaxle is a shaft, wither stationary or rotating, nor subjected to torsion load. A shirt rotating shaft is often called a spindle. When either the lateral or the torsional deflection of a shaft must be held to close limits, the shaft must be sized on the basis of deflection before analyzing the stresses. The reason for this is that, if the shaft is made stiff enough so that the deflection is not too large, it is probable that the resulting stresses will be safe. But by no means should the designer assume that they are safe; it is almost always necessary to calculatethem so that he knows they are within acceptable limits Whenever possible, the power-transruission elements, such as gears or pullets, should be located close to the supporting bearings, This reduces the bending moment, and hence the deflection and bending stress.Although the von Mises-Hencky-Goodman method is difficult to use in design of shaft, it probably comes closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaft-design problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heat-treatment, and surface finish and whether or not shot peening is necessary in order to achieve the required life and reliability Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake two in ertias 11 and 12 traveling at the respective angular velocities Wl and W2, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake. Slippage occurs because the two elements are running at different speeds and energy is dissipated during actuation, resulting in a temperature rise. In analyzing the performance of these devices we shall beinterested in the actuating force, the torque transmitted, the energy loss and the temperature rise. The torque transmitted is related to the actuating force, the coefficient of friction, and the geometry of the clutch or brake. This is problem in static, which will have to be studied separately for eath geometric configuration. However, temperature rise is related to energy loss and can be studied without regard to the type of brake or clutch because the geometry of interest is the heat-dissipating surfaces. The various types of clutches and brakes may be classified as fllows1. Rim type with internally expanding shoes2. Rim type with externally contracting shoes3。

机械制造专业外文翻译-轴、联轴器和滚动轴承

外文原文：shafts、couplings and rolling contact bearingskey words: shafts、couplings、bearingsVirtually all machines contain shafts.The most common shape for shafts is circular and the cross section can be either solid or hollow (hollow shafts can result in weight savings ).Rectangular shafts are sometimes used ,as in screwdriver blades,socket wrenches and control knob stems .A shaft must have adequate torsional strength to transmit torque and not be overstressed. It also be torsionally stiff enough so that one mounted component does not deviate excessively from its original angular position relative to a second component mounted on the same shaft. Generally speaking ,the angle of twist should not exceed one degree in a shaft length equal to 20 diameters.Shafts are mounted inbearings and transmint power through such devices as gears, pullerys, cams and clutches. These devices introduce forces which attempt to bend the shaft; hence, the shaft must be rigid enough to prevent overloading of the supporting bearings. In general, the bending deflection of a shaft should not exceed 0.01 in. per ft of length between bearing supports.In addition, the shaft must be able to sustain a combination of bending and torsional loads. Thus an equivalent load must be consideredwhich takes into account both torsion and bending. Also, the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur.For diameters less than 3 in. , the usual shaft material is cold-rolled ateel containing about 0.4 percent carbon. Shafts are either cold-rolled or forged in sizes from 3 in. to 5 in. ,shafts are forged and machined to size .Pleastic shafts are widely used for light load applications. One advantage of using plastic is safety in electrical applications ,since plastic is a poor conductor of electricity.Components such as gears and pulleys are mounted on shafts by means of key .The design of the key and the corresponding keyway in the shaft must be prperly evaluated. For example ,stress concentrations occur in shafts due to keyways ,and the material removed to form the keyway further weakens the shaft.If shafts are run at cirtical speeds ,severe vibrations can occur which can seriously damage a machine. It is important to know the magnitude of these critical speeds so that they can be avoided. As a general rule of thumb,the difference between the operating speed and the critical speed should be at least 20 percent .Another important aspect of shaft design is the method of directly connecting one shaft to another. This is accomplished by devices such as rigid and flexible couplings.A coupling is a device for connecting the eds of adjacent shafts. In machine construction, ouplings are used to effect a semipermanent connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the machine, but it can be broken and restored in an emergency or when worn parts are replaced.There are several types of shaft couplings, their characteristics depend on the purpose for which they are used. If an exceptionally long shaft is required in a manufacturing plant or a propeller shaft on a ship, it is made in sections that are coupled together with rigid couplings. A common type of rigid coupling consists of two mating radial flanges(disks) that are cttached by key-driven hubs to the eds of adjacent shaft sections and bolted together through the flanges to form a rigid connection. Alignment of the connected shafts is usually effeted by means of a rabbet joint on the face of the flanges.In connecting shafts belonging to separate devices (such as an electric motor and a gearbox ),precise aligning of the shafts is difficult and a flexible coupling is used. This coupling connects theshafts in such a way as to minimize the harmful effects of shaft misalignment. Flexible couplings also permit the shafts to deflect under their separate systems of with one another. Flexible couplings can also serve to reduce the intensity of shock loads and vibrations transmitted from one shaft to another.Virtually all shafts contain rolling contact bearings.The concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to load; (b) stiffness ,i.e. deflections under load; (c) friction;(d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will usually secure satisfactory performance. The deflection of the bearing elements will become important where loads are high, although this is usuallyof less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard the hostility of the environment.Because the high quality and low price of ball and roller bearings depends on quantity production, the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with ateel which is through-hardened toabout 900HV,although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600 HV. It is not surprising that, owing to the high stresses involved, a predominant form of failure should be metal fatigue, and a good deal of work is currently in progress intended to improve the reliability of this type of bearing. Design can bebased on accepted values of life and it is generral practice in the bearing industry to define the load capacity of the bearing as that value below which 90 lpercent of a batch will exceed a lift of ane million revolutions.Notwithstanding the fact that responsibility for the basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by abutting against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provides with a radius or chamfer to allow space for this .Where life is not the determining factor in design, it is usual to determine maximum loading by the amount towhich a bearing will deflect under load. Thus the concept of “static load-carrying capacity” is understood to mean the load that can be alpplied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has beendetermined by practical experience as the load which when applied to a bearing results in a total deformation of the rolling element and raceway at any point of contact not exceeding 0.01 percent of the rolling-element diameter. This would correspond to a permanent deformation of 0.00025 mm for a ball 25mm in diameter.The successful functioning of many bearing depends upon providing them with adequate protection against their environment, and in some circumstances the enviroration of the bering surfaces. Achievement of the correct functioning of seals is an essential part of bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on the basis of the approlpriate bearing theory. Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.References:1 Erickson.Belt and Application for Engineers.Marcel Dekker.Inc,19972 South,Mancuso.Mechanical Power Transmission Components.1994中文译文：轴、联轴器和滚动轴承关键词：轴、联轴器、轴承实际上，几乎所有的机器中都装有轴。

齿轮和轴的介绍外文文献翻译、中英文翻译

XX设计(XX)外文资料翻译院系专业学生姓名班级学号外文出处Manufacturing Engineering andTechnology-Machining附件：1.外文资料翻译译文（约3000汉字）；2.外文资料原文(与课题相关的1万印刷符号左右)。

附件1：外文资料翻译译文齿轮和轴的介绍摘要在传统机械和现代机械中齿轮和轴的重要地位是不可动摇的。

齿轮和轴主要安装在主轴箱来传递力的方向。

通过加工制造它们可以分为许多的型号，分别用于许多的场合。

所以我们对齿轮和轴的了解和认识必须是多层次多方位的。

关键词:齿轮；轴在直齿圆柱齿轮的受力分析中，是假定各力作用在单一平面的。

我们将研究作用力具有三维坐标的齿轮。

因此，在斜齿轮的情况下，其齿向是不平行于回转轴线的。

而在锥齿轮的情况中各回转轴线互相不平行。

像我们要讨论的那样，尚有其他道理需要学习，掌握。

斜齿轮用于传递平行轴之间的运动。

倾斜角度每个齿轮都一样，但一个必须右旋斜齿，而另一个必须是左旋斜齿。

齿的形状是一渐开线螺旋面。

如果一张被剪成平行四边形（矩形）的纸张包围在齿轮圆柱体上，纸上印出齿的角刃边就变成斜线。

如果我展开这张纸，在血角刃边上的每一个点就发生一渐开线曲线。

直齿圆柱齿轮轮齿的初始接触处是跨过整个齿面而伸展开来的线。

斜齿轮轮齿的初始接触是一点，当齿进入更多的啮合时，它就变成线。

在直齿圆柱齿轮中，接触是平行于回转轴线的。

在斜齿轮中，该先是跨过齿面的对角线。

它是齿轮逐渐进行啮合并平稳的从一个齿到另一个齿传递运动，那样就使斜齿轮具有高速重载下平稳传递运动的能力。

斜齿轮使轴的轴承承受径向和轴向力。

当轴向推力变的大了或由于别的原因而产生某些影响时，那就可以使用人字齿轮。

双斜齿轮（人字齿轮）是与反向的并排地装在同一轴上的两个斜齿轮等效。

他们产生相反的轴向推力作用，这样就消除了轴向推力。

当两个或更多个单向齿斜齿轮被在同一轴上时，齿轮的齿向应作选择，以便产生最小的轴向推力。

外文翻译---齿轮的设计、制造和应用

毕业设计(论文)外文资料翻译学院：专业：机械设计制造及其自动化姓名：学号：外文出处： Mechanism and Machine Theory34 (1999) 857-876(用外文写)附件： 1.外文资料翻译译文；2.外文原文。

附件1：外文资料翻译译文动力传动圆锥渐开线齿轮的设计、制造和应用Dr. J. Börner,K. Humm,Dr. F. Joachim,Dr. H. akaria,ZF Friedrichshafen AG , 88038Friedrichshafen, Germany；[摘要]圆锥渐开线齿轮(斜面体齿轮)被用于交叉或倾斜轴变速器和平行轴自由侧隙变速器中。

圆锥齿轮是在齿宽横断面上具有不同齿顶高修正(齿厚)的直齿或斜齿圆柱齿轮。

这类齿轮的几何形状是已知的，但应用在动力传动上则多少是个例外。

ZF公司已将该斜面体齿轮装置应用于各种场合:4W D轿车传动装置、船用变速器(主要用于快艇)机器人齿轮箱和工业传动等领域。

斜面体齿轮的模数在0. 7 mm-8 mm之间，交叉传动角在0°- 25°。

之间。

这些边界条件需要对斜面体齿轮的设计、制造和质量有一个深入的理解。

在锥齿轮传动中为获得高承载能力和低噪声所必须进行的齿侧修形可采用范成法磨削工艺制造。

为降低制造成本，机床设定和由于磨削加工造成的齿侧偏差可在设计阶段利用仿真制造进行计算。

本文从总体上介绍了动力传动变速器斜面体齿轮的研发，包括:基本几何形状、宏观及微观几何形状的设计、仿真、制造、齿轮测量和试验。

1前言在变速器中如果各轴轴线不平行的话，转矩传递可采用多种设计，例如:伞齿轮或冠齿轮、万向节轴或圆锥渐开线齿轮(斜面体齿轮)。

圆锥渐开线齿轮特别适用于小轴线角度(小于15°)，该齿轮的优点是在制造、结构特点和输入多样性等方而的简易。

圆锥渐开线齿轮被用于直角或交叉轴传动的变速器或被用于平行轴自由侧隙工况的变速器。

中英文文献翻译-轴和齿轮的设计及应用

机械制造毕业设计外文英文文献翻译齿轮和齿轮传动

机械制造毕业设计外文英文文献翻译齿轮和齿轮传动Gears and gear driveGears are the most durable and rugged of all mechanical drives. They can transmit high power at efficiencies up to 98% and with long service lives. For this reason, gears rather than belts or chains are found in automotive transmissions and most heavy-duty machine drives. On the other hand, gears are more expensive than other drives, especially if they are machined and not made from power metal or plastic.Gear cost increases sharply with demands for high precision and accuracy. So it is important to establish tolerance requirements appropriate for the application. Gears that transmit heavy loads or than operate at high speeds are not particularly expensive, but gears that must do both are costly.Silent gears also are expensive. Instrument and computer gears tend to be costly because speed or displacement ratios must be exact. At the other extreme, gears operating at low speed in exposed locations are normally termed no critical and are made to minimum quality standards.For tooth forms, size, and quality, industrial practice is to follow standards set up by the American Gear Manufactures AssociationAGMA.Tooth formStandards published by AGMA establish gear proportions and tooth profiles. Tooth geometry is determined primarily by pitch, depth, and pressure angle.Pitch：Standards pitches are usually whole numbers when measured as diametral pitch P. Coarse-pitch gearing has teeth larger than 20 diametral pitch ?usually 0.5 to 19.99. Fine-pitch gearing usually has teeth of diametral pitch 20 to 200.Depth: Standardized in terms of pitch. Standard full-depth have working depth of 2/p. If the teeth have equal addendaas in standard interchangeable gears the addendum is 1/p. Stub teeth have a working depth usually 20% less than full-depth teeth. Full-depth teeth have a larger contract ratio than stub teeth. Gears with small numbers of teeth may have undercut so than they do not interfere with one another during engagement. Undercutting reduce active profile and weakens the tooth.Mating gears with long and short addendum have larger load-carrying capacity than standard gears. The addendum of the smaller gear pinion is increased while that of larger gear is decreased, leaving the whole depth the same. This form is know as recess-action gearing.Pressure Angle: Standard angles are and . Earlier standards include a 14-pressure angle that is still used. Pressure angle affectsthe force that tends to separate mating gears. High pressure angle decreases the contact ratio ratio of the number of teeth in contact but provides a tooth of higher capacity and allows gears to have fewer teeth without undercutting.Backlash: Shortest distances between the non-contacting surfaces of adjacent teeth .Gears are commonly specified according to AGMA Class Number, which is a code denoting important quality characteristics. Quality number denote tooth-element tolerances. The higher the number, the closer the tolerance. Number 8 to 16 apply to fine-pitch gearing.Gears are heat-treated by case-hardening, through-hardening, nitriding, or precipitation hardening. In general, harder gears are stronger and last longer than soft ones. Thus, hardening is a device that cuts the weight and size of gears. Some processes, such as flame-hardening, improve service life but do not necessarily improve strength.Design checklistThe larger in a pair is called the gear, the smaller is called the pinion.Gear Ratio: The number of teeth in the gear divide by the number of teeth in the pinion. Also, ratio of the speed of the pinion to the speed of the gear. In reduction gears, the ratio of input to output speeds.Gear Efficiency: Ratio of output power to input power. includesconsideration of power losses in the gears, in bearings, and from windage and churning of lubricant.Speed: In a given gear normally limited to some specific pitchline velocity. Speed capabilities can be increased by improving accuracy of the gear teeth and by improving balance of the rotating parts.Power: Load and speed capacity is determined by gear dimensions and by type of gear. Helical and helical-type gears have the greatest capacity to approximately 30,000 hp. Spiral bevel gear are normally limited to 5,000 hp, and worm gears are usually limited to about 750 hp.Special requirementsMatched-Set Gearing: In applications requiring extremely high accuracy, it may be necessary to match pinion and gear profiles and leads so that mismatch does not exceed the tolerance on profile or lead for the intended application.Tooth Spacing: Some gears require high accuracy in the circular of teeth. Thus, specification of pitch may be required in addition to an accuracy class specification.Backlash: The AMGA standards recommend backlash ranges to provide proper running clearances for mating gears. An overly tight mesh may produce overload. However, zero backlash is required in some applications.Quiet Gears: To make gears as quit as possible, specify thefinest pitch allowable for load conditions. In some instances, however, pitch is coarsened to change mesh frequency to produce a more pleasant, lower-pitch sound. Use a low pressure angle. Use a modified profile to include root and tip relief. Allow enough backlash. Use high quality numbers. Specify a surface finish of 20 in. or better. Balance the gear set. Use a nonintegral ratio so that the same teeth do not repeatedly engage if both gear and pinion are hardened steel. If the gear is made of a soft material, an integral ratio allows the gear to cold-work and conform to the pinion, thereby promoting quiet operation. Make sure critical are at least 20% apart from operating speeding or speed multiples and from frequency of tooth mesh.Multiple mesh gearMultiple mesh refers to move than one pair of gear operating in a train. Can be on parallel or nonparallel axes and on intersection or nonintersecting shafts. They permit higer speed ratios than are feasible with a single pair of gears .Series trains:Overall ratio is input shaft speed divided by output speed ,also the product of individual ratios at each mesh ,except in planetary gears .Ratio is most easily found by dividing the product of numbers of teeth of driven gears by the product of numbers of teeth of driving gears.Speed increasers with step-up rather than step-down ratios mayrequire special care in manufacturing and design. They often involve high speeds and may creste problems in gear dynamics. Also, frictional and drag forces are magnified which, in extreme cases , may lead to operational problems.Epicyclic Gearing:Normally, a gear axis remains fixed and only the gears rotates. But in an epicyclic gear train, various gears axes rotate about one anther to provide specialized output motions. With suitable clutchse and brakes, an epicyclic train serves as the planetary gear commonly found in automatic transmissions.Epicyclic trains may use spur or helical gears, external or internal, or bevel gears. In transmissions, the epicyclic or planetary gears usually have multiple planets to increase load capacity.In most cases, improved kinematic accuracy in a gearset decreases gear mesh excitation and results in lower drive noise. Gearset accuracy can be increased by modifying the tooth involute profile, by substituting higher quality gearing with tighter manufacturing tolerances, and by improving tooth surface finish. However, if gear mesh excitation generaters resonance somewhere in the drive system, nothing short of a “perfect” gearset will substantially reduce vibration and noise.Tooth profiles are modified to avoid interferences which can result from deflections in the gears, shafts, and housing as teeth engageand disendgage. If these tooth interferences are not compensated for by profile modifications, gears load capacity can be seriously reduced. In addition, the drive will be noisier because tooth interferences generate high dynamic loads. Interferences typically are eliminated by reliving the tooth tip, the tooth flank, or both. Such profile modifications are especially important for high-load , high-speed drives. The graph of sound pressure levelvs tip relief illustrates how tooth profile modifications can affect overall drive noise. If the tip relief is less than this optimum value, drive noise increases because of greater tooth interference; a greater amount of tip relief also increase noise because the contact ratio is decreased.Tighter manufacturing tolerances also produce quietier gears. Tolerances for such parameters as profile error, pitch AGMA quality level. For instance, the graph depicting SPL vs both speed and gear quality shows how noise decreases example, noise is reduced significantly by an increase in accuracy from an AGMA Qn 11 quality to an AGNA Qn 15 quality. However, for most commercial drive applications, it is doubtful that the resulting substantial cost increase for such an accuracy improvement can be justified simply on the basis of reduced drive noise.Previously, it was mentioned that gears must have adequate clearance when loaded to prevent tooth interference during the course of meshing. Tip and flank relief are common profile modifications thatcontrol such interference. Gears also require adequate backlash and root clearance. Noise considerations make backlash an important parameter to evaluate during drive design. Sufficient backlash must be provided under all load and temperature conditions to avoid a tight mesh, which creates excessively high noise level. A tight mesh due to insufficient backlash occurs when the drive and coast side of a tooth are in contact simultaneously. On the other hand, gears with excessive backlash also are noisy because of impacting teeth during periods of no load or reversing load. Adequate backlash should be provided by tooth thinning rather than by increase in center distance. Tooth thinning dose not decrease the contact ratio, whereas an increase in center distance does. However, tooth thinning does reduce the bending fatigue, a reduction which is small for most gearing systems.齿轮和齿轮传动在所有的机械传动形式中，齿轮传动是一种最结实耐用的传动方式。

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机械类外文翻译—轴和齿轮的设计及应用摘要在传统机械和现代机械中齿轮和轴的重要地位是不可动摇的。

齿轮和轴主要安装在主轴箱来传递力的方向。

通过加工制造它们可以分为许多的型号，分别用于许多的场合。

所以我们对齿轮和轴的了解和认识必须是多层次多方位的。

关键词:齿轮；轴在直齿圆柱齿轮的受力分析中，是假定各力作用在单一平面的。

我们将研究作用力具有三维坐标的齿轮。

因此，在斜齿轮的情况下，其齿向是不平行于回转轴线的。

而在锥齿轮的情况中各回转轴线互相不平行。

像我们要讨论的那样，尚有其他道理需要学习，掌握。

斜齿轮用于传递平行轴之间的运动。

倾斜角度每个齿轮都一样，但一个必须右旋斜齿，而另一个必须是左旋斜齿。

齿的形状是一溅开线螺旋面。

如果一张被剪成平行四边形（矩形）的纸张包围在齿轮圆柱体上，纸上印出齿的角刃边就变成斜线。

如果我展开这张纸，在血角刃边上的每一个点就发生一渐开线曲线。

直齿圆柱齿轮轮齿的初始接触处是跨过整个齿面而伸展开来的线。

斜齿轮轮齿的初始接触是一点，当齿进入更多的啮合时，它就变成线。

在直齿圆柱齿轮中，接触是平行于回转轴线的。

在斜齿轮中，该先是跨过齿面的对角线。

它是齿轮逐渐进行啮合并平稳的从一个齿到另一个齿传递运动，那样就使斜齿轮具有高速重载下平稳传递运动的能力。

斜齿轮使轴的轴承承受径向和轴向力。

当轴向推力变的大了或由于别的原因而产生某些影响时，那就可以使用人字齿轮。

双斜齿轮（人字齿轮）是与反向的并排地装在同一轴上的两个斜齿轮等效。

他们产生相反的轴向推力作用，这样就消除了轴向推力。

当两个或更多个单向齿斜齿轮被在同一轴上时，齿轮的齿向应作选择，以便产生最小的轴向推力。

交错轴斜齿轮或螺旋齿轮，他们是轴中心线既不相交也不平行。

交错轴斜齿轮的齿彼此之间发生点接触，它随着齿轮的磨合而变成线接触。

因此他们只能传递小的载荷和主要用于仪器设备中，而且肯定不能推荐在动力传动中使用。

交错轴斜齿轮与斜齿轮之间在被安装后互相捏合之前是没有任何区别的。

它们是以同样的方法进行制造。

一对相啮合的交错轴斜齿轮通常具有同样的齿向，即左旋主动齿轮跟右旋从动齿轮相啮合。

在交错轴斜齿设计中，当该齿的斜角相等时所产生滑移速度最小。

然而当该齿的斜角不相等时，如果两个齿轮具有相同齿向的话，大斜角齿轮应用作主动齿轮。

蜗轮与交错轴斜齿轮相似。

小齿轮即蜗杆具有较小的齿数，通常是一到四齿，由于它们完全缠绕在节圆柱上，因此它们被称为螺纹齿。

与其相配的齿轮叫做蜗轮，蜗轮不是真正的斜齿轮。

蜗杆和蜗轮通常是用于向垂直相交轴之间的传动提供大的角速度减速比。

蜗轮不是斜齿轮，因为其齿顶面做成中凹形状以适配蜗杆曲率，目的是要形成线接触而不是点接触。

然而蜗杆蜗轮传动机构中存在齿间有较大滑移速度的缺点，正像交错轴斜齿轮那样。

蜗杆蜗轮机构有单包围和双包围机构。

单包围机构就是蜗轮包裹着蜗杆的一种机构。

当然，如果每个构件各自局部地包围着对方的蜗轮机构就是双包围蜗轮蜗杆机构。

着两者之间的重要区别是，在双包围蜗轮组的轮齿间有面接触，而在单包围的蜗轮组的轮齿间有线接触。

一个装置中的蜗杆和蜗轮正像交错轴斜齿轮那样具有相同的齿向，但是其斜齿齿角的角度是极不相同的。

蜗杆上的齿斜角度通常很大，而蜗轮上的则极小，因此习惯常规定蜗杆的导角，那就是蜗杆齿斜角的余角；也规定了蜗轮上的齿斜角，该两角之和就等于90度的轴线交角。

当齿轮要用来传递相交轴之间的运动时，就需要某种形式的锥齿轮。

虽然锥齿轮通常制造成能构成90度轴交角，但它们也可产生任何角度的轴交角。

轮齿可以铸出，铣制或滚切加工。

仅就滚齿而言就可达一级精度。

在典型的锥齿轮安装中，其中一个锥齿轮常常装于支承的外侧。

这意味着轴的挠曲情况更加明显而使在轮齿接触上具有更大的影响。

另外一个难题，发生在难于预示锥齿轮轮齿上的应力，实际上是由于齿轮被加工成锥状造成的。

直齿锥齿轮易于设计且制造简单，如果他们安装的精密而确定，在运转中会产生良好效果。

然而在直齿圆柱齿轮情况下，在节线速度较高时，他们将发出噪音。

在这些情况下，螺旋锥齿轮比直齿轮能产生平稳的多的啮合作用，因此碰到高速运转的场合那是很有用的。

当在汽车的各种不同用途中，有一个带偏心轴的类似锥齿轮的机构，那是常常所希望的。

这样的齿轮机构叫做准双曲面齿轮机构，因为它们的节面是双曲回转面。

这种齿轮之间的轮齿作用是沿着一根直线上产生滚动与滑动相结合的运动并和蜗轮蜗杆的轮齿作用有着更多的共同之处。

轴是一种转动或静止的杆件。

通常有圆形横截面。

在轴上安装像齿轮，皮带轮，飞轮，曲柄，链轮和其他动力传递零件。

轴能够承受弯曲，拉伸，压缩或扭转载荷，这些力相结合时，人们期望找到静强度和疲劳强度作为设计的重要依据。

因为单根轴可以承受静压力，变应力和交变应力，所有的应力作用都是同时发生的。

“轴”这个词包含着多种含义，例如心轴和主轴。

心轴也是轴，既可以旋转也可以静止的轴，但不承受扭转载荷。

短的转动轴常常被称为主轴。

当轴的弯曲或扭转变形必需被限制于很小的范围内时，其尺寸应根据变形来确定，然后进行应力分析。

因此，如若轴要做得有足够的刚度以致挠曲不太大，那么合应力符合安全要求那是完全可能的。

但决不意味着设计者要保证；它们是安全的，轴几乎总是要进行计算的，知道它们是处在可以接受的允许的极限以内。

因之，设计者无论何时，动力传递零件，如齿轮或皮带轮都应该设置在靠近支持轴承附近。

这就减低了弯矩，因而减小变形和弯曲应力。

虽然来自M.H.G方法在设计轴中难于应用，但它可能用来准确预示实际失效。

这样，它是一个检验已经设计好了的轴的或者发现具体轴在运转中发生损坏原因的好方法。

进而有着大量的关于设计的问题，其中由于别的考虑例如刚度考虑，尺寸已得到较好的限制。

设计者去查找关于圆角尺寸、热处理、表面光洁度和是否要进行喷丸处理等资料，那真正的唯一的需要是实现所要求的寿命和可靠性。

由于他们的功能相似，将离合器和制动器一起处理。

简化摩擦离合器或制动器的动力学表达式中，各自以角速度w1和w2运动的两个转动惯量I1和I2，在制动器情况下其中之一可能是零，由于接上离合器或制动器而最终要导致同样的速度。

因为两个构件开始以不同速度运转而使打滑发生了，并且在作用过程中能量散失，结果导致温升。

在分析这些装置的性能时，我们应注意到作用力，传递的扭矩，散失的能量和温升。

所传递的扭矩关系到作用力，摩擦系数和离合器或制动器的几何状况。

这是一个静力学问题。

这个问题将必须对每个几何机构形状分别进行研究。

然而温升与能量损失有关，研究温升可能与制动器或离合器的类型无关。

因为几何形状的重要性是散热表面。

各种各样的离合器和制动器可作如下分类：1．轮缘式内膨胀制冻块；2．轮缘式外接触制动块；3．条带式；4．盘型或轴向式；5．圆锥型；6．混合式。

分析摩擦离合器和制动器的各种形式都应用一般的同样的程序，下面的步骤是必需的：1．假定或确定摩擦表面上压力分布；2．找出最大压力和任一点处压力之间的关系；3．应用静平衡条件去找寻（a）作用力；（b）扭矩；(c)支反力。

混合式离合器包括几个类型，例如强制接触离合器、超载释放保护离合器、超越离合器、磁液离合器等等。

强制接触离合器由一个变位杆和两个夹爪组成。

各种强制接触离合器之间最大的区别与夹爪的设计有关。

为了在结合过程中给变换作用予较长时间周期，夹爪可以是棘轮式的，螺旋型或齿型的。

有时使用许多齿或夹爪。

他们可能在圆周面上加工齿，以便他们以圆柱周向配合来结合或者在配合元件的端面上加工齿来结合。

虽然强制离合器不像摩擦接触离合器用的那么广泛，但它们确实有很重要的运用。

离合器需要同步操作。

有些装置例如线性驱动装置或电机操作螺杆驱动器必须运行到一定的限度然后停顿下来。

为着这些用途就需要超载释放保护离合器。

这些离合器通常用弹簧加载，以使得在达到预定的力矩时释放。

当到达超载点时听到的“喀嚓”声就被认定为是所希望的信号声。

超越离合器或连轴器允许机器的被动构件“空转”或“超越”，因为主动驱动件停顿了或者因为另一个动力源使被动构件增加了速度。

这种离合器通常使用装在外套筒和内轴件之间的滚子或滚珠。

该内轴件，在它的周边加工了数个平面。

驱动作用是靠在套筒和平面之间契入的滚子来获得。

因此该离合器与具有一定数量齿的棘轮棘爪机构等效。

磁液离合器或制动器相对来说是一个新的发展，它们具有两平行的磁极板。

这些磁极板之间有磁粉混合物润滑。

电磁线圈被装入磁路中的某处。

借助激励该线圈，磁液混合物的剪切强度可被精确的控制。

这样从充分滑移到完全锁住的任何状态都可以获得。

加工基础作为产生形状的一种加工方法，机械加工是所有制造过程中最普遍使用的而且是最重要的方法。

机械加工过程是一个产生形状的过程，在这过程中，驱动装置使工件上的一些材料以切屑的形式被去除。

尽管在某些场合，工件无承受情况下，使用移动式装备来实现加工，但大多数的机械加工是通过既支承工件又支承刀具的装备来完成。

机械加工在知道过程中具备两方面。

小批生产低费用。

对于铸造、锻造和压力加工，每一个要生产的具体工件形状，即使是一个零件，几乎都要花费高额的加工费用。

靠焊接来产生的结构形状，在很大程度上取决于有效的原材料的形式。

一般来说，通过利用贵重设备而又无需特种加工条件下，几乎可以以任何种类原材料开始，借助机械加工把原材料加工成任意所需要的结构形状，只要外部尺寸足够大，那都是可能的。

因此对于生产一个零件，甚至当零件结构及要生产的批量大小上按原来都适于用铸造、锻造或者压力加工来生产的，但通常宁可选择机械加工。

严密的精度和良好的表面光洁度，机械加工的第二方面用途是建立在高精度和可能的表面光洁度基础上。

许多零件，如果用别的其他方法来生产属于大批量生产的话，那么在机械加工中则是属于低公差且又能满足要求的小批量生产了。

另方面，许多零件靠较粗的生产加工工艺提高其一般表面形状，而仅仅是在需要高精度的且选择过的表面才进行机械加工。

例如内螺纹，除了机械加工之外，几乎没有别的加工方法能进行加工。

又如已锻工件上的小孔加工，也是被锻后紧接着进行机械加工才完成的。

基本的机械加工参数刀具的基本关系是以以下四个要素来充分描述的：刀具的几何形状，切削速度，进给速度，和吃刀深度。

切削刀具必须用一种合适的材料来制造，它必须是强固、韧性好、坚硬而且耐磨的。

刀具的几何形状——以刀尖平面和刀具角为特征——对于每一种切削工艺都必须是正确的。

切削速度是切削刃通过工件表面的速率，它是以每分钟英寸来表示。

为了有效地加工，切削速度高低必须适应特定的工件——刀具配合。

一般来说，工件材料越硬，速度越低。

进给速度是刀具切进工件的速度。

若工件或刀具作旋转运动，进给量是以每转转过的英寸数目来度量的。

当刀具或工件作往复运动时，进给量是以每一行程走过的英寸数度量的。

一般来说，在其他条件相同时，进给量与切削速度成反比。