YB32-200型压力机液压系统的设计【含CAD高清图纸和文档所见所得】
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本科生毕业设计专业外文翻译原 文: Hydraulic cylinders 译 文: 液压缸 指导教师 : 王菡 职称: 讲师 学生姓名 : 张 亮 学号:1102130432 专 业 : 机械设计制造及其自动化 院(系) : 机电工程学院 2015年4月10日Hydraulic cylindersHydraulic cylinders are hydraulic energy into mechanical energy, make a linear reciprocating motion (or swing movement) of the hydraulic actuators. Simple structure, reliable work. Use it to achieve reciprocating motion, can be removed from deceleration devices, and no transmission gap, smooth movement, and therefore widely used in various mechanical hydraulic system. Hydraulic cylinder output force and the effective area of the piston and the pressure is proportional to both sides; consisting essentially of hydraulic cylinders and cylinder head, piston and piston rod, seals, cushioning device component and exhaust. Cushioning device and the exhaust depending on the specific application may be, other devices are essential.One . TypeAccording to the form of the structure of a conventional hydraulic cylinder, which can be divided into three types: structural forms sanitation garbage truck hydraulic cylinder varied, there are a variety of classification methods: by movement can be divided into linear reciprocating and rotary swing ; by the liquid-pressure situation can be divided into single-acting and double-acting; form of the structure can be divided into piston, piston, multi-stage telescoping; rack and pinion, etc; can be divided according to the installation form for rod, earrings, foot, hinge shaft; pressure level can be divided according to 16Mpa, 25Mpa, 31.5Mpa so on.PistonSingle rod cylinder is only one end of the piston rod. As shown is a single hydraulic cylinder piston. Both ends of the import and export of oil through ports A and B can pressure oil or oil return to two-way movement, it is known as double-acting cylinders.Only one-way movement of the piston, the opposite direction from the force required to complete. But its stroke hydraulic cylinder piston generally more big.Hydraulic cylinder piston worksHydraulic cylinder piston rod can be divided into single and double rod two structures fixed by way of fixed and fixed two cylinder piston rod, according to the role of fluid pressure in the case of a single-acting and double-acting. In a single-acting hydraulic cylinder, the pressure oil chamber is for a hydraulic cylinder, by hydraulic pressure of the cylinder to achieve a single direction of movement, the movement in the opposite direction by an external force (e.g. spring force, its own weight or external loads, etc.) to achieve; and bis acting hydraulic cylinder piston movement in both directions through the two chambers alternately into the oil, by the action of hydraulic pressure to complete.Plunger(1) piston hydraulic cylinder is a single-acting hydraulic cylinder, hydraulic pressure can only be achieved by a direction of movement of the plunger return to rely on other external or plunger weight;(2) does not support the piston and cylinder liner rely on contact, so that the liner easily processed, it is suitable for making long-stroke hydraulic cylinders;(3) working the plunger of the total pressure, so it must have sufficient rigidity;(4) tend to be larger piston weight, easy to sag due to its own weight when placed horizontally, causing the seal and guide unilateral wear, so the vertical use of more favorable.TelescopicTelescopic hydraulic cylinder piston has two or more stages, telescopic hydraulic cylinder piston out of style in descending order, while the load is normally retracted the order from small to large. Telescopic cylinders can achieve a longer stroke, while retraction length is shorter, more compact structure. Such cylinders commonly used in the construction machinery and agricultural machinery. There are a plurality of primary motion of the piston, each piston during successive movement, the output speed and output power are changing.SwingSwing hydraulic cylinder is an actuator output torque and to achieve a reciprocating motion, also called the swing hydraulic motor. There are two forms of single and double leaf blades. The stator is fixed to the cylinder block, and the blades and rotor are connected together. According inlet direction, will drive the rotor blades for reciprocating swing.Two . buffer deviceUsed in the hydraulic system having a hydraulic cylinder driving mechanism of a certain quality, having a large kinetic energy when the hydraulic cylinder is moved to the stroke end, the Failing deceleration process, the hydraulic cylinder piston and the cylinder head will occur mechanical impact, an impact, noise, there destructive. To mitigate and prevent such harm occurs, it can be set up in the hydraulic circuit deceleration device or in the cylinder equipped with cushioning devices.Three . ProcessingCylinder as the main components of hydraulic cylinders, single pillar mining, hydraulic support, barrel and other products, and its processing quality directly affects the entire product life and reliability. Cylinder high processing requirements, the inner surface roughness is Ra0.4 0.8 & um, concentricity, wear resistance demanding. The basic characteristics of the cylinder is the deep processing, the processing has been plagued by processing staff.Using rolling processing, leaving the surface because the surface layer of residual compressive stress, helps a closed surface microcracks, impede erosion expansion. Thereby enhancing the corrosion resistance of the surface, and can delay fatigue cracks or expanded, thus increasing the fatigue strength of the cylinder. By roll forming, cold rolling the surface layer of the hardened layer, the elastic and plastic deformation to reduce the grinding surface of the auxiliary contact, thereby improving the wear resistance of the inner wall of the cylinder, while avoiding burns caused by grinding. After rolling, the reduction of the surface roughness can be improved with the nature.Cylinder is a mechanical engineering major parts, the traditional processing methods are: Broaching cylinder - fine boring cylinder - grinding cylinder. Using rolling method is: Broaching cylinder - fine boring cylinder - rolling cylinder, step three parts, but the contrast in time: grinding cylinder about 1 m in 1-2 days, rolling cylinder 1 meter in about 10-30 minutes. Investment comparison: quilting grinder or mill (tens of thousands - millions), rolling knife (a thousand - tens of thousands). After rolling, the surface roughness of the hole by rolling before Ra3.2 6.3um buildings reduced to Ra0.4 0.8 & surface hardness um, hole by about 30%, the cylinder surface fatigue strength by 25%. If only consider the cylinder cylinder life impact, increased by 2 to 3 times rolling process is relatively boring grinding efficiency is about 3 times. The above data shows that the rolling process is efficient and can greatly improve the surface quality of the cylinder.After rolling the cylinder surface is no small sharp edge for a long time and will not damage the movement friction seals or seals, which is especially important in the hydraulic industry.Four . Diagnosis and treatment1, A malfunction or failure of the actionCauses and treatment methods are the following:(1) spool valve stuck or clogging. When the flow direction of the valve spool valve or valve stuck or clogging, hydraulic cylinders prone to malfunction or failure of the operation. You should check the oil pollution; check whether dirt or gelatinous precipitates stuck valve or blockage of the valve hole; check valve wear, cleaning, changing the system filter, cleaning the tank, replace the hydraulic medium.(2) the piston rod and cylinder or a hydraulic cylinder jammed blockage. At this point in any case manipulation, or action hydraulic cylinder does not operate even micro. Then check the piston and piston rod seal is tight, whether to enter the dirt and glial sediment: the axis of the piston rod and the cylinder is on, the wearing parts and seals if failure load carried it too great.(3) control the hydraulic system pressure is too low. Throttling resistance in the control line may be too large, improper flow regulating valve, the control pressure is inappropriate, the pressure source is disturbed. You should check the control pressure source, ensure that the pressure is adjusted to the specified value of the system.(4) in the hydraulic system into the air. Mainly because the system has a leak. You should check the hydraulic oil tank level, seals and fittings suction side of the pump, suction strainer is dirty. If so, you should add hydraulic oil, seals and fittings handle, clean or replace the coarse filter.(5) hydraulic cylinder initial slow. At lower temperatures, the hydraulic oil viscosity, poor mobility, resulting in slow hydraulic cylinder. Improvement approach is to replace the good viscosity-temperature performance of hydraulic oil at low temperatures can make use of the heater or heating oil with the machine itself to raise start-up, the system work the oil temperature should be maintained at around 40 .2, when the work can not drive the loadMainly for piston stop bit inaccurate, insufficient thrust, speed drops, job insecurity, etc. The reason is:(1) hydraulic cylinder internal leakage. Internal leakage of hydraulic cylinders including hydraulic cylinder seals, rod seals and piston seals and closures are due to wear and tear such as excessive leakage.The reason piston seal leakage and closures that seal wrinkles, squeezing, tearing, abrasion, aging, deterioration, distortion, etc., and you should be replaced with new seals.Piston seal wear is mainly due to excessive speed control valve to adjust properly, causing excessive back pressure and seal improperly installed or hydraulic oil contamination. Followed by a foreign substance enters the assembly and sealing materials is not good quality. The consequence is slow, weak, can also cause serious damage to the piston and the cylinder, a pull-cylinder phenomenon. Approach is to adjust the speed control valve, the control installation instructions shall make the necessary operations and improvements.(2) a hydraulic circuit leakage. Including valves and hydraulic piping leaks. Repair method is to check and eliminate leaking hydraulic valve connecting pipe through manipulation.(3) hydraulic oil through the relief valve bypass back to the tank. If the relief valve stuck into the dirt, so that the relief valve normally open, hydraulic oil will pass through the relief valve directly back into the tank, causing no oil into the cylinder. If the load is too large, adjust the pressure relief valve has exceeded the maximum rating, but still not the thrust hydraulic cylinder continuous action without action required. If you adjust the lower pressure, due to insufficient pressure is still not up to the required load vertebral strength, showed enough thrust. You should check and adjust the pressure relief valve.3, the piston sliding or crawlingHydraulic cylinder piston sliding or crawling make hydraulic cylinders unstable. The main reasons are:(1) internal stagnation and hydraulic cylinders. Cylinder internal parts improper assembly, parts deformation, wear or geometric tolerance overrun, the resistance movement is too large, the hydraulic cylinder piston speed varies with changes in stroke position, slippage, or crawl. Mostly due to poor quality parts assembly, surface scratches or sintered iron produced, so that the resistance increases, the rate of decline. For example: a piston rod bending and different heart or rod, the rod of the hydraulic cylinder or rail mounting position offset, seal ring fitted too tight or too loose and so on. The workaround is to re-repair or adjustment, replacement parts and remove iron damage.(2) poor lubrication or hydraulic cylinder aperture processing tolerance. Because such as the piston and cylinder, the piston rod guide and have relative motion, if poor lubrication or hydraulic cylinder aperture ultra-poor, will be increased wear, so the cylinder centerline straight decreases. Thus, when the hydraulic cylinder piston work, friction will be large, sometimes small, slip or crawl. Pre-ground approach is to exclude hydraulic cylinders, then meet the requirements of the preparation of the piston, the piston rod grinding, configuration guide sleeve.(3) the hydraulic pump or a hydraulic cylinder into the air. Air compression or expansion will cause the piston sliding or crawling. Remedy is to check the pump, set up a special exhaust, fast travel back and forth several times to exhaust the whole operation.(4) the seal of quality and is directly related to slip or crawl. O-rings when used at a low pressure, compared with the U-shaped ring, due to the higher surface pressure, the difference between static and dynamic friction large, prone to slippage or creeping; U-ring seal surface pressure with increasing pressure is increased, although the sealing effect is increased accordingly, but the difference between static and dynamic frictional resistance becomes large, the internal pressure increases, the impact of rubber elasticity, since the contact resistance is increased lip, the lip seals will rollover and elongation, also prone to slip or crawl, to prevent it tipping support ring can maintain its stability.液压缸液压缸是将液压能转变为机械能的、做直线往复运动(或摆动运动)的液压执行元件。它结构简单、工作可靠。用它来实现往复运动时,可免去减速装置,并且没有传动间隙,运动平稳,因此在各种机械的液压系统中得到广泛应用。液压缸输出力和活塞有效面积及其两边的压差成正比;液压缸基本上由缸筒和缸盖、活塞和活塞杆、密封装置、缓冲装置与排气装置组成。缓冲装置与排气装置视具体应用场合而定,其他装置则必不可少。1类型根据常用液压缸的结构形式,可将其分为三种类型:环卫垃圾车的液压缸的结构形式多种多样,其分类方法也有多种:按运动方式可分为直线往复运动式和回转摆动式;按受液压力作用情况可分为单作用式、双作用式;按结构形式可分为活塞式、柱塞式、多级伸缩套筒式;齿轮齿条式等;按安装形式可分为拉杆、耳环、底脚、铰轴等;按压力等级可分为16Mpa、25Mpa、31.5Mpa等。活塞式 单活塞杆液压缸只有一端有活塞杆。如图所示是一种单活塞液压缸。其两端进出口油口A和B都可通压力油或回油,以实现双向运动,故称为双作用缸。活塞仅能单向运动,其反方向运动需由外力来完成。但其行程一般较活塞式液压缸大。活塞式液压缸的工作原理活塞式液压缸可分为单杆式和双杆式两种结构,其固定方式由缸体固定和活塞杆固定两种,按液压力的作用情况有单作用式和双作用式。在单作用式液压缸中,压力油只供液压缸的一腔,靠液压力使缸实现单方向运动,反方向运动则靠外力(如弹簧力、自重或外部载荷等)来实现;而双作用液压缸活塞两个方向的运动则通过两腔交替进油,靠液压力的作用来完成。柱塞式 (1)柱塞式液压缸是一种单作用式液压缸,靠液压力只能实现一个方向的运动,柱塞回程要靠其它外力或柱塞的自重;(2)柱塞只靠缸套支承而不与缸套接触,这样缸套极易加工,故适于做长行程液压缸;(3)工作时柱塞总受压,因而它必须有足够的刚度;(4)柱塞重量往往较大,水平放置时 容易因自重而下垂,造成密封件和导向单边磨损,故其垂直使用更有利。伸缩式伸缩式液压缸具有二级或多级活塞,伸缩式液压缸中活塞伸出的顺序式从大到小,而空载缩回的顺序则一般是从小到大。伸缩缸可实现较长的行程,而缩回时长度较短,结构较为紧凑。此种液压缸常用于工程机械和农业机械上。有多个一次运动的活塞,各活塞逐次运动时,其输出速度和输出力均是变化的。双作用单活塞杆式液压缸摆动式摆动式液压缸是输出扭矩并实现往复运动的执行元件,也称摆动式液压马达。有单叶片和双叶片两种形式。定子块固定在缸体上,而叶片和转子连接在一起。根据进油方向,叶片将带动转子作往复摆动。2缓冲装置在液压系统中使用液压缸驱动具有一定质量的机构,当液压缸运动至行程终点时具有较大动能,如未作减速处理,液压缸活塞与缸盖将发生机械碰撞,产生冲击、噪声,有破坏性。为缓和及防止这种危害发生,因此可在液压回路中设置减速装置或在缸体内设缓冲装置。3加工缸筒作为液压缸、矿用单体支柱、液压支架、炮管等产品的主要部件,其加工质量的好坏直接影响整个产品的寿命和可靠性。缸筒加工要求高,其内表面粗糙度要求为Ra0.40.8&um,对同轴度、耐磨性要求严格。缸筒的基本特征是深孔加工,其加工一直困扰加工人员。采用滚压加工,由于表面层留有表面残余压应力,有助于表面微小裂纹的封闭,阻碍侵蚀作用的扩展。从而提高表面抗腐蚀能力,并能延缓疲劳裂纹的产生或扩大,因而提高缸筒疲劳强度。通过滚压成型,滚压表面形成一层冷作硬化层,减少了磨削副接触表面的弹性和塑性变形,从而提高了缸筒内壁的耐磨性,同时避免了因磨削引起的烧伤。滚压后,表面粗糙度值的减小,可提高配合性质。油缸是工程机械最主要部件,传统的加工方法是:拉削缸体精镗缸体磨削缸体。采用滚压方法是:拉削缸体精镗缸体滚压缸体,工序是3部分,但时间上对比:磨削缸体1米大概在1-2天的时间,滚压缸体1米大概在10-30分钟的时间。投入对比:磨床或绗磨机(几万几百万),滚压刀(1仟几万)。滚压后,孔表面粗糙度由幢滚前Ra3.26.3um减小为Ra0.40.8&um,孔的表面硬度提高约30%,缸筒内表面疲劳强度提高25%。油缸使用寿命若只考虑缸筒影响,提高23倍,镗削滚压工艺较磨削工艺效率提高3倍左右。以上数据说明,滚压工艺是高效的,能大大提高缸筒的表面质量。油缸经过滚压后,表面没有锋利的微小刃口,长时间的运动摩擦也不会损伤密封圈或密封件,这点在液压行业特别重要。4.故障诊断及处理1、误动作或动作失灵原因和处理方法有以下几种:(1)阀芯卡住或阀孔堵塞。当流量阀或方向阀阀芯卡住或阀孔堵塞时,液压缸易发生误动作或动作失灵。此时应检查油液的污染情况;检查脏物或胶质沉淀物是否卡住阀芯或堵塞阀孔;检查阀体的磨损情况,清洗、更换系统过滤器,清洗油箱,更换液压介质。(2)活塞杆与缸筒卡住或液压缸堵塞。此时无论如何操纵,液压缸都不动作或动作甚微。这时应检查活塞及活塞杆密封是否太紧,是否进入脏物及胶质沉淀物:活塞杆与缸筒的轴心线是否对中,易损件和密封件是否失效,所带负荷是否太大。(3)液压系统控制压力太低。控制管路中节流阻力可能过大,流量阀调节不当,控制压力不合适,压力源受到干扰。此时应检查控制压力源,保证压力调节到系统的规定值。(4)液压系统中进入空气。主要是因为系统中有泄漏发生。此时应检查液压油箱的液位,液压泵吸油侧的密封件和管接头,吸油粗滤器是否太脏。若如此,应补充液压油,处理密封及管接头,清洗或更换粗滤芯。(5)液压缸初始动作缓慢。在温度较低的情况下,液压油黏度大,流动性差,导致液压缸动作缓慢。改善方法是,更换黏温性能较好的液压油,在低温下可借助加热器或用机器自身加热以提升启动时的油温,系统正常工作油温应保持在40左右。2、工作时不能驱动负载 主要表现为活塞杆停位不准、推力不足、速度下降、工作不稳定等,其原因是:(1)液压缸内部泄漏。液压缸内部泄漏包括液压缸体密封、活塞杆与密封盖密封及活塞密封均磨损过量等引起的泄漏。活塞杆与密封盖密封泄漏的原因是,密封件折皱、挤压、撕裂、磨损、老化、变质、变形等,此时应更换新的密封件。活塞密封过量磨损的主要原因是速度控制阀调节不当,造成过高的背压以及密封件安装不当或液压油污染。其次是装配时有异物进入及密封材料质量不好。其后果是动作缓慢、无力,严重时还会造成活塞及缸筒的损坏,出现“拉缸”现象。处理方法是调整速度控制阀,对照安装说明应做必要的操作和改进。(2)液压回路泄漏。包括阀及液压管路的泄漏。检修方法是通过操纵换向阀检查并消除液压连接管路的泄漏。(3)液压油经溢流阀旁通回油箱。若溢流阀进入脏物卡住阀芯,使溢流阀常开,液压油会经溢流阀旁通直接流回油箱,导致液压缸没油进入。若负载过大,溢流阀的调节压力虽已达到最大额定值,但液压缸仍得不到连续动作所需的推力而不动作。若调节压力较低,则因压力不足达不到仍载所需的椎力,表现为推力不够。此时应检查并调整溢流阀。3、活塞滑移或爬行液压缸活塞滑移或爬行将使液压缸工作不稳定。主要原因如下:(1)液压缸内部涩滞。液压缸内部零件装配不当、零件变形、磨损或形位公差超限,动作阻力过大,使液压缸活塞速度随着行程位置的不同而变化,出现滑移或爬行。原因大多是由于零件装配质量差,表面有伤痕或烧结产生的铁屑,使阻力增大,速度下降。例如:活塞与活塞杆不同心或活塞杆弯曲,液压缸或活塞杆对导轨安装位置偏移,密封环装得过紧或过松等。解决方法是重新修理或调整,更换损伤的零件及清除铁屑。(2)润滑不良或液压缸孔径加工超差。因为活塞与缸筒、导轨与活塞杆等均有相对运动,如果润滑不良或液压缸孔径超差,就会加剧磨损,使缸筒中心线直线性降低。这样,活塞在液压缸内工作时,摩擦阻力会时大时小,产生滑移或爬行。排除办法是先修磨液压缸,再按配合要求配制活塞,修磨活塞杆,配置导向套。(3)液压泵或液压缸进入空气。空气压缩或膨胀会造成活塞滑移或爬行。排除措施是检查液压泵,设置专门的排气装置,快速操作全行程往返数次排气。(4)密封件质量与滑移或爬行有直接关系。O形密封圈在低压下使用时,与U形密封圈比较,由于面压较高、动静摩擦阻力之差较大,容易产生滑移或爬行;U型密封圈的面压随着压力的提高而增大,虽然密封效果也相应提高,但动静摩擦阻力之差也变大,内压增加,影响橡胶弹性,由于唇缘的接触阻力增大,密封圈将会倾翻及唇缘伸长,也容易引起滑移或爬行,为防止其倾翻可采用支承环保持其稳定。0
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