机电专业毕业设计相关文献翻译

Gear Gear (Gear) is relying on the tooth meshing torque rotavirus mechanical parts.Gear with other dentate machinery parts, such as a worm gear, rack, transmission, which can realize changed the direction of rotation speed and torque, change the direction of movement and change the movement forms, and other functions.Owing to the high transmission efficiency, accurate and advantages of large range of power transmission ratio, gear mechanism is widely used in industrial products, the design and manufacture level directly affects the quality of industrial products.Gear tooth buckle each gear will drive the other gears to transmit power.Separate two gears, chains can also be applied, caterpillar, on both sides of the belt to drive gear and transmission power. Basic introduction. In the application of transmission gear appeared very early.More than three hundred years BC, the ancient Greek philosopher Aristotle in the mechanical problems, it expounds the bronze or iron gear transmission problem of rotary motion.Invented in ancient China, has been applied in the entire gear train.However, the ancient gear is made of wood or metal moulds, can only transfer between shaft rotary motion, cannot guarantee the stability of transmission, the bearing capacity of the gear are also small.According to historical records, in 400 200 BC in ancient China has already started to use gear, shanxi unearthed bronze gears in our country is by far the oldest gear had been found, as a reflection of ancient science and technology achievements of this work is to gear mechanism as the core mechanism.The 17th century, people started to research, can be delivered right tooth shape of the movement.The 18th century, Europe after the industrial revolution, the application of gear transmission is increasing day by day widely；First the development of cycloidal gear, then the involute gear, until the beginning of the 20th century, involute gear has set up a file in the application. As early as in 1694, French scholar Philippe De La Hire forward involute tooth shape curve can be used as in the first place.In 1733, the French M.C amus put forward the common normal of tooth contact must be on the center of the node.A auxiliary instantaneous center line respectively along the big wheel and little wheel of the instantaneous center line (pitch) for pure rolling, and the auxiliary instantaneous center line solid coupling of auxiliary tooth shape on the big wheel and little wheel envelope formed by two tooth profile curve is conjugated to each other, this is Camus theorem.It takes into account the two tooth surface meshing state；Clearly established the modern concept about contact trajectory.In 1765, Swiss L.E uler involute profile analytic research mathematical foundation, illustrates a pair of meshing gears, the tooth profile curve of the radius of curvature and curvature center position.Later, babies further complete the method, and is now the Eu - let - babies equation.Can contribute to the application of involute tooth profile is Roteft WUlls, he put forward the centre distance change when involute gear has the advantages of the angular speed ratio unchanged.In 1873, a German engineer Hoppe is put forward, with different number of teeth of involute tooth profile of gear in the pressure Angle is changed, thus laid the ideological basis of modern shift gear. The end of the 19th century, generative principle of gear cutting method and using the principle of gear cutting machine and cutting tool appeared, after making the gear machining with the more comprehensive means, involute profile shows high more optimal sex.Teeth mesh as long as the gear cutting tools from the normal position when moving slightly, can use the standard cutter cut out the corresponding shift gears in machine tool.In 1908, the Swiss MAAG displacement method is studied and manufacturing export as processing gear shaper, later, the BSS, American AGMA, Germany DIN successively put forward many kinds of method to calculate the deflection of gear. In order to improve the service life of the power transmission gear and reduce its size, in addition to from material, heat treatment and structure improvement, the circular arc tooth profile of gear obtained the development.In 1907, the British Frank Humphris published a circular arc tooth profile at the earliest.In 1926, rui natives Eruest Wildhaber a patent on the method of surface arc tooth profile helical gears.In 1955, the Soviet unions M.L.N ovikov completed practical research of arc tooth profile gear and get the order of Lenin.In 1970, the British Rolh - Royce company engineers R.M.S tuder achieved double circular arc gear patent in the United States.This kind of gear is now increasingly attention by people, in the production of the show The benefits. Gear is to be able to mesh each other toothed machine part, its application in the field of mechanical transmission and the whole machinery is extremely broad.Modern gear technology has reached: the module of gear o. 004 100 mm；Gear diameter by 1 mm 150 m；On the transmitted power can reach hundreds of kilowatts；Speed up to hundreds of thousands of revolutions per minute；The circumference of the highest speed of 300 m/SEC. With the development of production, the gear operation stability.1674 Danish astronomer roemer first with outer cycloid tooth profile curve is put forward, in order to get stable running gear. In the 18th century industrial revolution, gear technology got rapid development, people have made a lot of research on gear.In 1733 the French mathematician card meters published profile meshing basic laws；In 1765 the Swiss mathematician euler proposed using involute tooth profile curve. Emerged in the 19th century gear hobbing machine and gear shaper, solves the problem of mass production and high precision gear.In 1900, ford for gear hobbing machine is installed on the differential device, can work out helical gear on gear hobbing machine, gear hobbing machine roll grinding wheel gained popularity, generating method processing gear of the landslide, gear involute gear become the most widely used. In 1899, pull up the first implementation of the project of the modified gear.Modified gear can not only avoid wheel tooth root cutting, can also gather together with center distance and improve the bearing capacity of the gear.In 1923 Americas Wilder Hubble first put forward the circular arc tooth profile of gear, 1955 Sue his circular-arc gear to carried on the thorough research, circular arc gear is applied in the production.The gear bearing capacity and efficiency is higher, but it is not as good as involute gear that is easy to manufacture, it remains to be further improved. Structure is introduced. Usually have a tooth, tooth, end face, the method of the surface, addendum circle and dedendum circle circle, dividing circle. 1) tooth, tooth for short, is the gear Every one for the convex part of the mesh, the convex part generally radiating arrangement, pairing the teeth of gear contact each other, can make the gears mesh continuous operation； 2) the tooth, is the space between the two adjacent teeth on the gears；End face is cylindrical or cylindrical worm gear, plane perpendicular to the axis of the gear or worm3) method, is perpendicular to the plane of the gears tooth line 4) addendum circle, is refers to the tooth top round 5) dedendum circle, refers to the bottom of the channel in the round 6) base circle, the formation of involute lines for pure rolling of round 7) dividing circle, it is in the end calculate the benchmark circular gear geometry size. Gear tooth profile can be, the gear shape, tooth shape, tooth surface and manufacturing methods such as classification. Gear tooth profile including tooth profile curve, pressure Angle, depth and deflection.Involute gear is relatively easy to manufacture, so the modern use of gear involute gear majority, with less cycloidal gear and circular-arc gear applications. In the aspect of pressure Angle, the bearing capacity of small pressure Angle gear smaller；And pressure Angle of gear, though bearing capacity is higher, but under the same in the transmission torque of bearing the load increase, so only for special situations.And gear tooth depth has been standardized, generally adopt high standard tooth.The advantage of deflection gear is more, in all kinds of mechanical equipment. In addition, the gear can also according to its shape can be divided into cylindrical gear, bevel gear, the non-circular gear, rack, worm, worm gear；According to the tooth line shape can be divided into straight gears, helical gears, herringbone gear, gear curve；According to the tooths surface is divided into external gear and internal gear；According to the manufacturing method can be divided into casting rolling gear, gear, gear cutting, sintered gear, etc. Gear manufacturing materials and heat treatment process on the gear bearing capacity and size weight has a great influence.Until the 1950 s, gear use carbon steel, the 60 s to switch to alloy steel, and multi-purpose surface hardened steel in the 70 s.According to the hardness, tooth surface can be divided into soft and hard tooth face two kinds of tooth surfaces. Bearing capacity is low, soft tooth surface gear manufacturing more easily, but good running-in, more restrictions on the size and weight without strict for transmission, and a small amount in the production of general machinery.Because the gear pairs, relatively heavy burden on small wheels, so in order to make the working life of the gear is roughly equal size, small tooth surface hardness is higher than the big wheel. Hard tooth surface gear of high bearing capacity, it is after the gear precision cutting, then quenching, surface hardening or carburizing and quenching treatment, in order to improve the hardness.But, in the heat treatment deformation of gear will inevitably produce, so after heat treatment must grind or fine cutting, grinding, to eliminate the error because of the deformation and improve the precision of gear. Material composition Commonly used steel manufacturing gear quenched and tempered steel, hardened steel, carburizing and quenching steel and nitriding steel.Slightly lower than the strength of the cast steel forging steel, used to size the larger gear；Mechanical properties of gray cast iron is bad, can be used for the open gear transmission in light load；Nodular cast iron can partially replace steel manufacturing gear；Plastic gear is used for light load and more requirements of low noise, and its gear pairs, the thermal conductivity is commonly used in steel gears. Future gear is overloaded, high speed, high precision and high efficiency, such as direction, and strive to small size, light weight, long service life and economic and reliable. And gear theory and the development of the manufacturing process will be further study the mechanism for tooth damage, this is to establish a reliable basis for the strength calculation method, is to improve the gear bearing capacity and extend the life of the gear theoretical foundation；Development represented by circular arc tooth profile of the new tooth form；Study of new gear material and the new process to make gear；Study of the elastic deformation of gear, manufacturing and installation error and the distribution of temperature field, to carry on the modification of gear tooth, so as to improve gear running stability, and increase the contact area of tooth, when loaded with so as to improve the bearing capacity of the gear. Friction and lubrication theory is a basic work in gear research and lubrication technology, research on elastic hydrodynamic pressure lubrication theory, promoting the synthetic lubricating oil and properly join extreme pressure additives in the oil, not only can improve the bearing capacity of tooth surface, and also can improve the transmission efficiency. 1, the tooth surface abrasion For open gear transmission or contain dont clean lubricating oil closed gear drive, due to the relative sliding between the meshing tooth surfaces, make some hard grinding grain into the friction surface, so that the tooth profile change, lateral clearance increased, lead to tooth gear so that the excessive thinning.In general, only when mixed abrasive in lubricating oil, will cause tooth surfaces of abrasive wear in the running. 2, tooth surface glue For high-speed heavy-load gear in the gear transmission, because of the friction between the tooth surface is larger, relative velocity, the meshing area temperature is exorbitant, once, and the bad lubrication condition between tooth surfaces of the oil film will disappear, make two tooth surface of the metal contact, mutual bonding to occur.When the two tooth face continue to relative motion, a hard tooth face will be part of the tooth surface of soft material off to form grooves along the sliding direction. 3, fatigue pitting Mutual engagement of two tooth contact, action and reaction between the tooth surface contact stress makes the work surface, the position of the mesh point is the change, and the gear do is periodic motion, so the contact stress is change according to the pulse cycle.Tooth surface for a long time under the effect of the alternating contact stress, the mark will appear small cracks in the gear tooth surface, with the passage of time, this kind of crack on the surface horizontal extension, gradually after the annular crack formation, the tooth surface of the small area of spalling and form a shallow pit some fatigue. 4, tooth broken In running projects to bear load gear as cantilever beam, its roots by the pulse of periodic stress exceeds the fatigue limit of the gear material, will produce crack in the root, and gradually expand, when unable to withstand a load transmission occurs when the rest of broken teeth phenomenon.Gear due to severe shock, partial load and in the work material Uneven may also cause the tooth broke. 5, tooth surface plastic deformation Under the impact load or overloading, tooth surface are prone to local plastic deformation, thus make involute tooth profile of the surface deformation. The development of Chinas gear industry Chinas gear industry got rapid development in the 15 during: gear industry output value in 2005 to increase 2000 yuan from 24 billion yuan in 2000, the compound annual growth rate of 23.27%, in a mechanical components has become Chinas largest industry.In terms of market demand and the scale of production, Chinas gear industry in the world ranking has been more than Italy, fourth in the world. In 2006, the Chinese all gears, transmission and drive components manufacturing enterprises achieve the cumulative gross industrial output value of 102.628183 billion yuan, a year-on-year growth of 24.15% over the same；Implementation accumulative total sales income of 98.23824 billion yuan, a year-on-year growth of 24.37% over the same；Implementation accumulative total profit of 5.66521 billion yuan, a year-on-year growth of 26.85% over the same. 1 - December 2007, the Chinese all gears, transmission and drive components manufacturing enterprises achieve the cumulative gross industrial output value of 136.542841 billion yuan, a year-on-year growth of 30.96% over the same；October 1-2008, the Chinese all gears, transmission and drive components manufacturing enterprises achieve the cumulative gross industrial output value of 144.529138 billion yuan, a year-on-year growth of 32.92% over the same. China gear manufacturing compared with the developed countries there is insufficient capacity for independent innovation, new product development is slow, the market competition, enterprise management is weak, the informationization level is low, the staff overall quality improvement.Gear industry at present stage should through the market competition and integration, improve the industry concentration, forming a group to have billions of yuan, 500 million yuan, 100 million yuan assets in large, medium and small enterprises；With independent intellectual property rights, product design and development, forming a batch of vehicle transmission system (transmission and drive axle assembly) led by enterprise, with leading enterprises supporting capacity and the power of the gear industry resource integration；Realize specialization, network, forming a large number of distinctive technique, distinctive products and rapid response ability of famous brand enterprises；Through technical renovation, to modernize the gear manufacturing enterprise transformation. At the end of the period of 11th five-year plan, China gear manufacturing sales can reach 130 billion yuan, per capita sales rose to 650000 yuan/year, industry in the world ranking of the worlds second.In 2006-2010 will be 100000 sets of new equipment, investment of about 6 billion yuan a year for new equipment, new machine 20000 units, each unit price 300000 yuan on average.By 2010, China gear manufacturing should be about 400000 various types of machine tools, among them 100000 sets of CNC machine, numerical control rate was 25% (17% higher than that of mechanical manufacture the industry average). Medium-duty truck gears Medium-duty truck gear with steel grades more in our country, mainly in order to adapt to the introduction of foreign advanced automotive technology at the time.50 s in our country from the former Soviet union, geoff medium-sized truck plant the introduction of the Soviet union (that is, the liberation brand original models) production technology at the same time, also introduced the former Soviet union in the production of automobile gear 20 crmnti steel grade. After the reform and opening up, with the rapid development of Chinas economic construction, in order to meet the requirements of the rapid development of transportation in our country, starting in the 80 s, our country in a planned way to introduce all kinds of advanced industrial developed countries, all kinds of foreign advanced medium-duty truck is introduced.At the same time, large car factory in China with foreign famous automobile companies to cooperate, the introduction of foreign advanced automobile manufacturing technology, including automobile gear production technology.At the same time, Chinas iron and steel smelting technology level has been improved, based on ladle and secondary smelting composition adjustment and continuous casting and rolling and other advanced smelting technology, makes the steel mill to produce high purity and hardenability band narrow gear steel, so as to realize the localization of the introduction of automobile gear steel, gear steel in our countrys production level on a new step.In recent years, suitable for Chinas national conditions of domestic heavy automobile gear can use nickel high hardenability steel also obtained the development and application, has obtained the good effect.Automobile gear heat treatment technology is also from the original 50-60 - s well type gas carburizing and applied to the current widely used by the computer control of continuous gas carburizing automatic line and box-type multi-purpose furnace and automatic production lines, including low pressure vacuum carburizing technology), the gear carburizing oxidation processing technology, control gear quenching cooling technology (due to the use of special oil quenching and quenching cooling technology), gear forging stock isothermal normalizing technology, etc.These technologies, not only make the gear carburizing and quenching distortion has been effectively controlled, the gear machining accuracy was improved, prolong the service life, but also can meet the needs of the modernization of the gear with the mass production of the heat treatment. Literatures, points out that the service life of automobile gear is mainly composed of two major index evaluation, one is the gear contact fatigue strength and bending fatigue strength of gear.The former is mainly decided by carburizing and quenching quality, which is mainly determined by the gear material.Therefore, it is necessary for automobile gear with the requirement of carburizing steel, properties and heat treatment characteristics a more comprehensive understanding. 9.19 chromium manganese steel and titanium boron steel Long-term since, our country is the most commonly used types of steel truck gear 20 crmnti.This is introduced in the 1950 s in China from the former Soviet union medium-sized automobile gear 18 XTR steel (i.e., 20 crmnti steel).This steel of fine grains, grain growth tendency when carburizing is small, has a good performance of carburizing and quenching, direct quenching after carburizing.Literature points out that in 1980 years ago, our country of carburized alloy structural steel, including 20 crbinti steel) in steel factory only guarantee steel was used to determine the mechanical properties, chemical composition and use but in auto production often appear when chemical composition and mechanical properties of qualified steel, due to the large hardenability can range and affect the quality of products.For example if 20 crmnti carburizing steel hardenability is too low, is made of the gear after carburizing and quenching, heart hardness is lower than the technical conditions of numerical value, fatigue test, the fatigue life of gear lower half；If high hardenability can, the gear inner hole shrinkage after carburizing and quenching which affect the gear assembly. Due to steel hardenability on the core hardness and distortion of gear has the extremely significant effect, metallurgical department in 1985 issued the guarantee of our country hardenability structural steel technical conditions (GB5216-85), in the technical conditions on the, including 20 cxmntih, 20 MNVBH steel, the chemical composition of 10 kinds of carburizing steel, hardenability data.Specified in the standard: 20 crmnti steel hardenability can be used in the manufacture of gear indicator for water-cooled end the hardness of 9 coffee place is from 30-42 HRC.After that, using 20 crmnti steel production hard was low and the distortion of gear teeth, the core is too big problem basically solved.But regardless of the size of the module of gear and steel section thickness all use the same steel grade 20 crmnti steel is obviously unreasonable.In recent years, due to the improvement of steel smelting technology in China and the improvement of alloy structural steel supply situation, has the condition of gear steel hardenability band further narrowed, and according to the different products (such as the transmission gear and rear axle gear, etc.) the requirements of the development of new steel grade to meet their requirements. Through consultation with steel mills in 1997, changchun faw has signed with the production of gear steel manufacturers will be 20 crmnti steel hardenability can FenDang supply agreement, such as liberated brand on the 5 t truck used in the manufacture of small size of cross section of the transmission shaft, intermediate shaft gear 1 and section size larger driving axle and driven bevel gear with 20 crmntih steel hardenability can category I and respectively, and the corresponding hardenability J9 respectively: 30-36 HRC and the J9 = 36 42 HRC. Around 1960, due to the tight supply of nickel, chromium steel in our country, affecting the nickel, chromium steel production in China.At a time when Chinas auto industry from the former Soviet union to introduce the technology, the Soviet union, a large amount of application of nickel, chromium steel.Therefore, when the development of Chinas auto industry to develop the boron steel, the development work, with 20 MNVB and 20 mn2tib steel instead of 20 crmnti carburizing steel gear manufacturing.This is because the add trace boron in steel (0.0001% 0.0035%) can significantly improve the hardenability of steel can, so join the trace boron in steel can substitute for a certain number of manganese, nickel, chromium, molybdenum and other precious metal elements, thus boron steel has been widely used.Changchun faw has been liberated brand automobile gear used in the production of 20 mntib and 20 mn2tib steel. Dongfeng automobile company production of dongfeng brand 5, cargo auto transmission and driving axle gear, respectively, using 20 crmnti and 20 MNVB steel manufacturing.Similarly, also signed with the steel mill, steel hardenability band narrow and along the supply agreement.Transmission and driving axle and driven bevel gear steel 20 crmntih respectively 20 MNVBH (3) and (2), 20 MNVBH (3), the corresponding hardenability can respectively 32 39 HRC and the J9 J9 = = 37 44 HRC, J9 = 34 42 HRC. The qijiang count gear works in our country has introduced the German companys heavy auto transmission gear production technology, in the domestic German company standards of development the company Cr - Mn - B boron steel gear to be successful.The hardenability of gear material can J10 = 31 39 HRC 9.19 chromium manganese steel and titanium boron steel Long-term since, our country is the most commonly used types of steel truck gear 20 crmnti.This is introduced in the 1950 s in China from the former Soviet union medium-sized automobile gear 18 XTR steel (i.e., 20 crmnti steel).This steel of fine grains, grain growth tendency when carburizing is small, has a good performance of carburizing and quenching, direct quenching after carburizing.Literature points out that in 1980 years ago, our country of carburized alloy structural steel, including 20 crbinti steel) in steel factory only guarantee steel was used to determine the mechanical properties, chemical composition and use but in auto production often appear when chemical composition and mechanical properties of qualified steel, due to the large hardenability can range and affect the quality of products.For example if 20 crmnti carburizing steel hardenability is too low, is made of the gear after carburizing and quenching, heart hardness is lower than the technical conditions of numerical value, fatigue test, the fatigue life of gear lower half；If high hardenability can, the gear inner hole shrinkage after carburizing and quenching which affect the gear assembly. Due to steel hardenability on the core hardness and distortion of gear has the extremely significant effect, metallurgical department in 1985 issued the guarantee of our country hardenability structural steel technical conditions (GB5216-85), in the technical conditions on the, including 20 cxmntih, 20 MNVBH steel, the chemical composition of 10 kinds of carburizing steel, hardenability data.Specified in the standard: 20 crmnti steel hardenability can be used in the manufacture of gear indicator for water-cooled end the hardness of 9 coffee place is from 30-42 HRC.After that, using 20 crmnti steel production hard was low and the distortion of gear teeth, the core is too big problem basically solved.But regardless of the size of the module of gear and steel section thickness all use the same steel grade 20 crmnti steel is obviously unreasonable.In recent years, due to the improvement of steel smelting technology in China and the improvement of alloy structural steel supply situation, has the condition of gear steel hardenability band further narrowed, and according to the different products (such as the transmission gear and rear axle gear, etc.) the requirements of the development of new steel grade to meet their requirements. Through consultation with steel mills in 1997, changchun faw has signed with the production of gear steel manufacturers will be 20 crmnti steel hardenability can FenDang supply agreement, such as liberated brand on the 5 t truck used in the manufacture of small size of cross section of the transmission shaft, intermediate shaft gear 1 and section size larger driving axle and driven bevel gear with 20 crmntih steel hardenability can category I and respectively, and the corresponding hardenability J9 respectively: 30-36 HRC and the J9 = 36 42 HRC. Around 1960, due to the tight supply of nickel, chromium steel in our country, affecting the nickel, chromium steel production in China.At a time when Chinas auto industry from the former Soviet union to introduce the technology, the Soviet union, a large amount of application of nickel, chromium steel.Therefore, when the development of Chinas auto industry to develop the boron steel, the development work, with 20 MNVB and 20 mn2tib steel instead of 20 crmnti carburizing steel gear manufacturing.This is because the add trace boron in steel (0.0001% 0.0035%) can significantly improve the hardenability of steel can, so join the trace boron in steel can substitute for a certain number of manganese, nickel, chromium, molybdenum and other precious metal elements, thus boron steel has been widely used.Changchun faw has been liberated brand automobile gear used in the production of 20 mntib and 20 mn2tib steel. Dongfeng automobile company production of dongfeng brand 5, cargo auto transmission and driving axle gear, respectively, using 20 crmnti and 20 MNVB steel manufacturing.Similarly, also signed with the steel mill, steel hardenability band narrow and along the supply agreement.Transmission and driving axle and driven bevel gear steel 20 crmntih respectively 20 MNVBH (3) and (2), 20 MNVBH (3), the corresponding hardenability can respectively 32 39 HRC and the J9 J9 = = 37 44 HRC, J9 = 34 42 HRC. The qijiang count gear works in our country has introduced the German companys heavy auto transmission gear production technology, in the domestic German company standards of development the company Cr - Mn - B boron steel gear to be successful.The hardenability of gear material can J10 = 31 39 HRC 9.19 chromium manganese steel and titanium boron steel Long-term since, our country is the most commonly used types of steel truck gear 20 crmnti.This is introduced in the 1950 s in China from the former Soviet union medium-sized automobile gear 18 XTR steel (i.e., 20 crmnti steel).This steel of fine grains, grain growth tendency when carburizing is small, has a good performance of carburizing and quenching, direct quenching after carburizing.Literature points out that in 1980 years ago, our country of carburized alloy structural steel, including 20 crbinti steel) in steel factory only guarantee steel was used to determine the mechanical properties, chemical composition and use but in auto production often appear when chemical composition and mechanical properties of qualified steel, due to the large hardenability can range and affect the quality of products.For example if 20 crmnti carburizing steel hardenability is too low, is made of the gear after carburizing and quenching, heart hardness is lower than the technical conditions of numerical value, fatigue test, the fatigue life of gear lower half；If high hardenability can, the gear inner hole shrinkage after carburizing and quenching which affect the gear assembly. Due to steel hardenability on the core hardness and distortion of gear has the extremely significant effect, metallurgical department in 1985 issued the guarantee of our country hardenability structural steel technical conditions (GB5216-85), in the technical conditions on the, including 20 cxmntih, 20 MNVBH steel, the chemical composition of 10 kinds of car