2407 冲压模具设计(1)
2407 冲压模具设计(1),冲压,模具设计
河南理工大学万方科技学院本科毕业设计(论文)开题报告题目名称 冲压模具设计学生姓名 王向华 专业班级 08 机械设计 5 班 学号 0816101043一、 选题的目的和意义 工业发展水平的不断提高,工业产品更新速度加快,对模具的要求越来越高,尽管改革开放以来,模具工业有了较大发展,但无论是数量还是质量仍满足不了国内市场的需要,目前满足率只能达到 70%左右。造成产需矛盾突出的原因,一是专业化、标准化程度低,除少量标准件外购外,大部分工作量均需模具厂去完成。加工企业管理的体制上的约束,造成模具制造周期长,不能适应市场要求。二是设计和工艺技术落后,如模具 CAD/CAM 技术采用不普遍,加工设备数控化率低等,亦造成模具生产效率不高、周期长。总之,是拖了机电、轻工等行业发展的后腿。模具影响着制品的质量。首先,模具型腔的形状、尺寸、表面光洁度、分型面、进浇口和排气槽位置以及脱模方式等对制件的尺寸精度和形状精度以及制件的物理性能、机械性能、电性能、内应力大小、各向同性性、外观质量、表面光洁度、气泡、凹痕、烧焦、银纹等都有十分重要的影响。其次,在加工过程中,模具结构对操作难以程度影响很大。在大批量生产塑料制品时,应尽量减少开模、合模的过程和取制件过程中的手工劳动,为此,常采用自动开合模自动顶出机构,在全自动生产时还要保证制品能自动从模具中脱落。另外模具对制品的成本也有影响。当批量不大时,模具的费用在制件上的成本所占的比例将会很大,这时应尽可能的采用结构合理而简单的模具,以降低成本。现代生产中,合理的加工工艺、高效的设备、先进的模具是必不可少是三项重要因素,尤其是模具对实现材料加工工艺要求、塑料制件的使用要求和造型设计起着重要的作用。高效的全自动设备也只有装上能自动化生产的模具才有可能发挥其作用,产品的生产和更新都是以模具的制造和更新为前提的。由于制件品种和产量需求很大,对模具也提出了越来越高的要求。因此促进模具的不断向前发展因此我们必须意识到,对模具设计的研究的目的和意义在于能够很好的认识模具工业在国民经济中的地位的重要性。因为利用模具成型零件的方法,实质上是一种少切削、无切削、多工序重合的生产方法,采用模具成型的工艺代替传统的切削加工工艺,可以提高生产效率,保证零件质量,节约材2料,降低生产成本,从而取得很高的经济效益。利用模具生产零件的方法已经成为工业上进行成批或大批生产的主要技术手段,它对保证制品质量,缩短试用周期,进而争先占领市场,以及产品更新换代和新产品开发都具有决定性的意义。因此德国把模具称为“金属加工中的帝王”,把模具工业视为“关键工业”,美国把模具称为“美国工业的基石”,把模具工业视为“不可估量其力量的工业”,日本把模具说成是“促进社会富裕繁荣的动力”,把模具视为“整个工业发展的秘密”。因此,要使国民经济各个部门获得高速发展,加速实现社会主义四个现代化,就必须尽快将模具工业搞上去,使模具生产形成一个独立的工业部门,从而充分发挥模具工业在国民经济中的关键作用二、 国内外研究综述:1、 国外(1) 级进模制造技术研究现状随着科学技术的不断进步,工业产品日益复杂与多样化,产品性能和质量也在不段提高,因而对冲压技术提出了更高的要求。冲压技术自身也在不断的创新和发展。为了适应大批量、高效率生产的需求,在冲压模具和设备上广泛应用了各种自动化的进、出料机构,对于大型冲压件,例如汽车覆盖件,专门配置了机械手或机器人,这不仅大大提高了冲压件的生产品质和生产率,而且也增加了冲压工作的安全性。在中、小件的大批量生产方面,现已广泛应用多工位级模、多工位压力机或高速压力机。在中、小批量多 品种生产方面,正在发展柔性制造系统,为了适应多品种生产时不断更换模具的需要,已成功地开发出快速换模系统。(2)多工位级进模的发展趋势随着工业产品质量的不断提高,冲压产品正呈现多品种、少批量、复杂、大型、精 密 等更新换代速度快的变化特点,冲压模具正向高效、精密、长寿命、大型化方向发展。为 适应市场变化,随着计算机技术和制造技术的迅速发展,冲压模具设计的制造技术也真有手工设计、依靠人工经验和常规机械加工技术向以计算机辅助设计(CAD) 、数3控切削技术、数控电加工为核心的计算机辅助设计与制造(CAD/CAM)技术转变。2、 国内 现代模具工业有“不衰亡工业”之称。世界模具市场总体上供不应求,市场需求量维持在600亿至650亿美元,同时,我国的模具产业也迎来了新一轮的发展机遇。近几年,我国模具产业总产值保持13%的年增长率(据不完全统计,2004年国内模具进口总值达到600多亿,同时,有近200个亿的出口),到2005年模具产值预计为600亿元,模具及模具标准件出口将从现在的每年9000多万美元增长到2005年的2亿美元左右。单就汽车产业而言,一个型号的汽车所需模具达几千副,价值上亿元,而当汽车更换车型时约有80%的模具需要更换。2003年我国汽车产销量均突破400万辆,预计2004年产销量各突破500万辆,轿车产量将达到260万辆。另外,电子和通讯产品对模具的需求也非常大,在发达国家往往占到模具市场总量的20%之多。目前,中国17000多个模具生产厂点,从业人数约50多万。1999年中国模具工业总产值已达245亿元人民币。工业总产值中企业自产自用的约占三分之二,作为商品销售的约占三分之一。在模具工业的总产值中,冲压模具约占50%,塑料模具约占33%,压铸模具约占6%,其它各类模具约占11%。三、 毕业设计(论文)所用的主要技术与方法:1、首先查阅相关的资料,了解与课题有关的背景知识2、查阅专业书籍,掌握课题设计的技术要点3、按照有关的计算公式进行计算4、用计算机绘图软件( CAD CAXA PRO/E)绘制主要零件图及三维图4四、 主要参考文献与资料获得情况:1黄毅宏著,模具制造工艺,北京 机械工业出版社,2000 年,1-42李发致著,模具先进制造技术,北京 机械工业出版社,2003 年,1-133高佩福著,实用模具制造技术,第二版,北京 中国轻工业出版社,2000 年4万战胜著,冲压工艺及模具设计,北京 中国铁道出版社,1995 年5模具实际与制造技术教育丛书编委会编,模具结构设计,机械工业出版社,2004 年6王树勋著,模具实用技术设计综合手册,广州 华南理工大学出版社,1995年五、 毕业设计(论文)进度安排(按周说明)1、1-4 周毕业实习(实习报告)2、5-7 周收集与课题相关的资料,熟悉课题背景,撰写开题报告.3、8-9 周进行方案论证,初步设计,绘制草图及初步计算4、10 周绘制装配图和主要零件图5、11 周撰写毕业设计说明书5六、 指导教师审批意见:指导教师: (签名)年 月 日 6河南理工大学万方科技学院本科毕业设计(论文)中期检查表指导教师: 张小明 职称: 所在院(系): 机械与动力工程学院 教研室(研究室): 题 目 冲压模具设计学生姓名 王 向 华 专业班级 08 机设 5 班 学号 0816101043一、选题质量:(主要从以下四个方面填写:1、选题是否符合专业培养目标,能否体现综合训练要求;2、题目难易程度;3、题目工作量;4、题目与生产、科研、经济、社会、文化及实验室建设等实际的结合程度)1、 选题与专业对口,课题的的设计,能综合训练专业知识与实践的结合2、 题目难度适中3、 题目工作量稍大4、 题目与工业生产联系紧密7二、开题报告完成情况:开题报告已完成三、阶段性成果:1、对冲压模具的国内外的发展与研究有所了解2、查阅了有关冲压模具的论文及科技期刊3、了解了冲压模具的有关计算及绘图四、存在主要问题:1、要对模具的三维建模要求较高2、绘图不易把握8五、指导教师对学生在毕业实习中,劳动、学习纪律及毕业设计(论文)进展等方面的评语指导教师: (签名)年 月 日STUDY ON SLIPPERS FOR RAW WATER HYDRAULIC AXIAL PISTONPUMPS AND MOTORS1. AbstractAs concerns for environmental compatibility, safetyand hygienic requirements, hydraulic systems using rawwater as pressure medium become more and moreattractive. A raw water hydraulic system has many advantages over conventional oil hydraulic systems,such as: environmentally compatibility, no pollution and no fire hazard, elimination of expensive oils with the associated problems of contamination, maintenance,storage, handling, elimination of the return hose, and elimination of health hazards, etc. But as a hydraulic medium, raw water has also drawbacks, such as very low viscosity, high vapor pressure, lack of lubrication and chemically active nature, etc., that all tend to promote problems of corrosion, wear, cavitation erosion, leakage, and so on, those problems must be overcome in the design and development of the raw water hydraulic components, especially the selection of materials and design of structure for the friction pairs in raw water hydraulic pumps and motors.The slipper/swashplate pair is one of the very important friction pairs in axial piston pumps and motors. Under the lubrication of raw water. materials for slipper/swashplate combination should have superior mechanical strength, low friction, resistance to corrosion, abrasion, cavitation erosion and sliding wear, and the structure of the slipper should be suitable for the characteristics of raw water and materials usedBased on authois researches, a new slipper foraxial piston pumps and motors is introduced in this paper. From tests with the slipper/swashplate lest rig, it shows that the new type slipper combined with appropriate swashplate has good tribological characteristics. This slipper can operate with raw water, even sea water. The successful study on slippers willprovide good helps for design and development of raw water hydraulic axial piston pumps and motors with higher performance.2. IntroductionThe use of water as hydraulic fluid is not new. The first hydraulic machine as a means of transmitting not only energy but also control signals is raw water hydraulic press that manufactured by Joseph Bramah in 1795, which marks the beginning of the age of modern applied hydraulics. After that almost 100 years raw water was used as hydraulic medium, until the beginning of 20th century the mineral oil began to take the place of raw water. Because of the much better lubrication and anti-corrosi on properbes of mineral oil as compared with raw water and the development of oil resistant sealing materials, oil hydraulics boosted quickly and raw water hydraulics was left behind, gradually acquiring the image of an obsolete technology.As concerns over safe or environmental issues a number of other hydraulic fluids have been developed over the past decades, such as synthetic base fluids, water base fluids, and vegetable oil base fluids, etc. These fluids have their own advantages and a certain range of applications. For a given application, engineers can make the hydraulic system have satisfactory performance by careful hydraulic fluid choice and system design. However, these hydraulic fluids also have its own shortcomings,so me shortcomings of these fluids are inherent and fatal. No one of these hydraulic fluids can meet the requirements of fire resistance and environmentally protection at the same time, and most of these fluids are very expensive.The re-emergence of using raw water as hydraulic fluid is mainly because of the following reasons.(1) Environmental Protection RequirementWithout strict adherence to specific control techniques, it is nearly impossible to eliminate the threat of leakage in hydraulic systems. Industry observers believe that as much as 85% of all hydraulic fluids eventually leave their systems through slow leaks, catastrophic line breaks, or failures of fittings and seals. The leakage of hydraulic fluids with some toxic chemical additives not only make working conditions messy and unsafe, but also can not be biodegradable and havepotential threat to the environment. Raw water has very good environmental compatibility and no pollution; water in the event of leakage eventually evaporates without leaving greasy or dirty residuals needs of applications for water hydraulics. The need of new applications is the intrinsic force of re-emergence and development of water hydraulics(2) Requirement of SafetyMineral oil are flammable, its leakage or spilling from systems may be result in a fire when in or near heat sources. Water is not flammable and does not present a fire hazard. In some areas, such as steel and glass production, iron making and foundry, injection molding, die casting, nuclear power, coal mining, etc. the requirement of safety is prime, so raw water hydraulics may be the best choice in the near future(3) Hygienic RequirementIn some fields, such as gold mining, food and medicine processing, water supply industry, etc , where escaping of oil or chemical additives from hydraulic systems can smear the product and damage the quality of manufactured product. Under these conditions, raw water is an ideal pressure medium.(4) Economy RequirementWater is available everywhere, needing no purchase, transport, storage, maintenance and disposal costs, so using water instead of mineral oil and other hydraulic fluids may offer tremendous economy. In ambient water environment, the system using raw water as hydraulic fluid can be designed as an open circuit.That means the return lines and water reservoir can beeliminated, further more the heater and the cooler of system are no longer needed, so the volume and weight of hydraulic equipment will reduced and the efficiency of system increased. If used underwater, such as in marine engineering, ocean exploration engineering, subsea equipment, underwater operation tools and robots, etc., water hydraulics can automatically counterbalance thewater hydrostatic head, this is very important for improving the efficiency and performance of thehydraulic systems.(5) Need of New ApplicationsAlong with the developments of modern science and technologies, many areas with special requirements provide many new opportunities of applications for water hydraulics. Such as fusion reactor equipment in nuclear power engineering, marine equipment and robots in ocean exploration engineering, etc, where the fire resistance, hygienic requirement, economy and environmental protection are all considered. Because of higher power density and smaller size of hydraulics than that of other power transmissions, there have urgent needs of applications for water hydraulics.The need of new applications is the intrinsic force of re-emergence and development of water hydraulics.3. Material SelectionThe slipper/swashplate pair is one of the very important friction pairs in axial piston pumps and motors. Under the lubrication of raw water,ingenious material selection is necessary.In a typical axial swashplate is stationary piston pump or motor, the swashplate is stationary ; the swashplate angle with the shaft centerline determines the length of the piston stroke (see Fig. 1)When using raw water as lubricant,according to rawwaters chemically active nature, low viscositylubrication and high vapor pressure,more problem should be considered.Firstly, raw water especially seawater is more aggressive , a large number of ions in seawater result in that seawater have much higher electric conductivity and may lead to electrochemistry erosion. The materials used for slipper and swashplate inevitably suffer aggressive corrosion from raw water , and the materials used for traditional oil hydraulic components will not be suitable here.Secondly, the kinematic viscosity of water at 50 is approximately 0.55cs ,which is less than 1/30 of the viscosity of a typical mineral oil fluid. The very low viscosity must increase the difficulty of developing hydrodynamic film between slipper and swashplate,and the very small change of waters viscosity with pressure means that elastohydrodynamic lubrication with hard materials is unlikely to occur. Hydraulic fluids with additives that aid in the boundary lubrication of contacting surface permit metal-on-metal contact without large amounts of surface damage or wear. Raw water contains on such additives and its lubrication is very poor. The poor lubrication of water is clearly one of its major dtawbacks, and will lead to increase contact fraction and possibly wear of contacting conponents. Indeed it is well documented that wear was the greatest problem experienced by the early users of water based fluids in axial piston pumps. Researches indicate that the elastohydrodynamic film of water is about 0.1m thick at 3m/s and 20-60, the elastohydtodynamic film of HWBF is about 0.15m thick at 0.191.27m/s and 23.5. So there are risks as high dry friction and strong wear between slipper and swashplate under the lubrication of raw water.Thirdly, the vapor pressure of water is much higher than that of mineral oil, which means that water boils or vaporizes much easier. Due to waters high vapor pressure and high velocity flow caused be waters low viscosity, the slipper and swashplate will be exposed to strong and fast cavitation erosion.So material selection for slipper/swashplate pair should depend on the operation conditions and the special properties of raw water. Materials for slipper/swashplate combination should have superior mechanical strength, low friction, resistance to aggressive corrosion, cavitation erosion,abrasion,and sliding wear, and should be easy available and cost low.4.Structure DesignThe structure design of slipper is very important as well as the material selection. The use of polymers as the material of slipper will derive a new problem-how to make the slipper wrap on the ball-shaped head of piston. Probably the solution is to use corrosion resistant metals combined with polymers. The slipper can be divided into two parts. One is slipper pad made of polymer, directly contact on the swashplate, its main function is making the slipper have good tribological properties. The other is shoe made of corrosion resistant alloy, its main function is making the slipper wrap on the ball-shaped head of piston. This structure can take the advantages of both metals ductility and polymers good tribological property(see Fig.2). The main static forces exerted on slipper are show in Fig.3. The force F acted on slipper from piston head includes hydrostatic force Fp on the piston end, spring force Fs, inertia force Fa of piston and slipper, and friction force Ff between piston and cylinder bore as formula:The reaction force N from swashplate can be divided into two components, component Nh of hydrostatic bearing force and component Nm of mechanical surface pressure,as following:N=Nh+NmThe relationship of N and F is:F=Ncos5.Conclusions Based on authors researches, some conclusions about material selection and structure design of slipper under lubrication of raw water can be summarized as following:(1) Slipper made of polymers combined with swashplate made of corrosion resistant alloys has superior tribological properties.(2) Cotton fiber-filled phenolics can be used to manufacture slipper for a certain application range of operation pressure below 14MPa.(3) The spring force exerted on slipper should be strong enough to keep about 0.10.2MPa contacting pressuer on the surfaces of slipper and swashplate.Farther tests are underway, and ceramics with good toughness will be introduced to manufacture slipper and swashplate. The experiences of study on slippers will provide good helps for design and development of raw water hydraulic axial piston pumps and motors.References1 Joseph L. Foszcz, Hydraulic Fluid Choices, Plant Engineering, (8),1996,68.2Li Zhuangyun, et al, Development of Hydraulic Pump to Operate with Raw water, Proceedings of ASME Fluid Engineering Division Summer Meeting, Washington DC, USA, June 21-25,1998.4吴仁荣,水润滑滑动轴承的设计计算,机电设备, (6) ,1997,30.5许耀铭,油膜理论与液压泵和马达的摩擦副设计,北京;机械工业出版社,1987.关于自然水液压轴向活塞泵和电动机的滑动部分的研究1.摘要基于环境和谐、安全和卫生需要的考虑,液压系统使用自然水作为压力介质这种现象变得越来越广泛。一个自然水液压系统相对于普通的油液压系统有很多优点,例如:环境和谐,没有污染,没有火的危害,与昂贵的油相关的危害、维护、贮存、管理问题的消除,返回塑料管的消除和健康危害的消除等等。但是作为液压系统的介质,自然水也有一些缺点,例如非常低的粘性,很高的水蒸气压力,缺少润滑和化学性自然等等,都加剧了腐蚀、磨损、气蚀侵蚀、泄露等问题,这些问题必须在设计和自然水液压元件的发展,尤其是材料和自然水液压泵和电动机的摩擦部分的结构设计中被克服。滑动部分/旋转罗盘部分是轴向活塞泵和电动机中的重要摩擦部分。在自然水的润滑下,滑动部分和旋转罗盘结合部分的材料应该较好的机械强度、低摩擦力、腐蚀的抵抗性、磨损、气蚀侵蚀和滑动摩擦,并且滑动部分的结构应该对于自然水和使用材料的特性是适合的。根据作者的研究,一种新型的用于轴向活塞泵和电动机上的滑块会在这篇文章中介绍。从滑块/旋转罗盘部分试验中表明这种新型的与合适旋转罗盘结合的滑块有着非常好的摩擦特性。这种滑块能够用自然水润滑,甚至是海水也可以。这个关于滑块的研究将会为自然水液压轴向活塞泵和电动机的更好发展提供好的帮助。2.介绍水用来作为液压流体已经不是新技术了。作为转换能源和控制信号的一种方式,第一台液压机器就是自然水液体压力,并且在 1795 年由杰瑟夫大量生产,同时也标志着现代液压时代的开始。在那之后几乎 100 年自然水被用作液压介质,直到 20 世纪的初期,油介质开始取代水介质。和自然水相比,油介质有更好的润滑和矿物油的抗腐蚀性,并且油抗性密封材料,油液压装置发展的很快,自然水液压装置就落后了,渐渐成为一种过时的技术了。基于在安全和环境问题方面的考虑,许多其他液压流体已经在过去的几十年发展了,例如合成来源液体、水来源液体和蔬菜油来源液体等等。这些液体有着它们各自的优点和确定的用途。对于一种给定的用途,工程师能够通过合理的液压流体选择和系统设计来使液压系统满足这个条件。然而,这些液压流体也存在着自身的缺点,其中的某些缺点是内在的并且是重大的。这些液压流体中没有一种能同时满足防火性和环保性的要求,同时大部分液体是很昂贵的。使用自然水作为液压流体主要由于以下几个原因:(1)环境保护的需要如果对于特殊控制技术没有严格的遵守,评估液压系统中的泄露威胁是不可能的。工业观察员相信所有液压流体中 85%的流体最后都是通过缓慢泄露、严重的连接破损或者设备和密封的故障而离开液压系统的。液压流体和一些有毒的化学添加剂的泄露不仅使工作条件混乱和不安全,同时也不能生物降解和对环境存在潜在的危害。自然水拥有很好的环境适应性并且没有污染;水在泄露后也会消失而没有油腻和脏的残留物。(2)安全的需要矿物油是可燃的,当周围有热源的时候它的泄露可能会导致起火。水是不可燃的,所以不会存在起火隐患。在一些区域,例如钢铁和玻璃生产,钢铁制造和铸造,注射模具,拉模铸造,核动力,采煤等等,对于安全的要求是主要的,因此自然水液压可能会成为将来的最好选择。(3)液压的需要在一些领域,例如金矿开采,事物和药品生产,水提供工业等等,这些由于油或者化学添加剂从液压系统中泄露而弄脏产品或是损害大批产品的质量,在这些条件下,自然水是一种理想的压力介质。(4)经济的需要水在很多地方都是存在的,不需要购买、运输、贮存、保持和清理成本,因此使用水代替矿物油和其他液压流体可以提供极大的经济性。在包围的水环境中,系统使用自然水作为液压流体能够被设计成开式循环。那意味着返回线和水储藏可以消除,加热和冷却系统也不再需要了,因此液压设备的容积和重量也会减少而系统的效率会增加。如果水下作业,例如在海运的工程上,海洋探索工程,海底设备,水下操作工具和机器人等等,水液压能够自动的抵消水静力的前端,这对于提高效率和液压系统的性能是很重要的。(5)新应用的需要随着现代科学和技术的发展,许多有着特殊需求的领域为水液压提供了很多运用的机遇。例如在核电工程中的核聚变反应装置,在海洋探索工程中的海运设备和机器人等等,这些地方需要考虑抗燃性,清洁的设备,经济性和环保等方面。和其它的能源转换相比,由于液压系统有较高的力密度和较小的尺寸,所以对于水液压的应用是迫切需要的。新应用的需要是水液压的出现和发展的内在反应。3材料选择滑动部分/旋转罗盘部分是轴向活塞泵和电动机中的重要摩擦部分。在自然水的润滑下,巧妙地选择材料是有必要的。在一个典型的轴向活塞泵或电动机中,旋转罗盘固定不动的,旋转罗盘与轴线的角度决定了活塞盘的长度。当使用自然水作为润滑剂时,由于自然水的化学活性自然,低粘性,润滑性差和较高的蒸汽压力,所以需要考虑很多问题。首先,自然水,尤其海水是活性的,海水中的大量离子导致海水有很强的导电性并且会导致电化学腐蚀。用在滑块和旋转罗盘上的材料会不可避免地遭到自然水的活性腐蚀,并且用于传统油液压器件也不适合用在这里。第二点,水的运动粘性在 50时接近 0.55cs,少于典型矿物油液体粘性的 1/30。过低的粘性一定会增加发展滑块和旋转罗盘之间水力薄层的困难程度,并且水的粘性伴随着压力的很小变化意味着硬质材料的流体动力润滑是不容易发生的。带有添加剂的液压流体使得金属与金属表面之间没有大量表面破坏或是磨损。自然水不包含如此多的添加剂并且它的润滑性是很差的。水的润滑性差很明显是它的一个主要缺点,并且会导致接触、破碎、和接触器件之间摩擦的加剧。事实上摩擦是早期用水作为轴向活塞泵的流体的使用者遇到的最大问题。研究表明水的流体弹性动力薄层在 3m/s 和 2060时大约是 0.1m 厚,HWBF 的流体弹性动力薄层在 0.191.27m/s 和 23.5时大约是 0.15m 厚。因此在自然水润滑下,滑块和旋转罗盘之间有干摩擦和强烈摩擦时会存在危险。 第三点,水的蒸汽压力要比矿物油的高很多,这意味着水沸腾或是蒸发会更加容易。由于水的高蒸汽压力和高速流动性由水的粘性地决定的,所以滑块和旋转罗盘会受到强烈和快速的气穴气蚀损害。因此,对于滑块和旋转罗盘部分材料的选择应该依据工作条件和自然水的特殊性质。滑块和旋转罗盘之间的连接部分应该有很好的机械强度、低摩擦、抗腐蚀性、和气穴气蚀、磨损和滑动摩擦,并且应该有很好的实用性和低成本。4.结构设计滑块的结构设计和材料的选择是同样重要的。用在滑块上的高分子材料会产生一个新的问题,就是怎样使滑块包围住活塞前端的球形部分。其中一个解决办法就是使用抗腐蚀材料与高分子材料连接。滑块可以分成两部分。一部分就是由高分子材料制成的滑块垫,直接与旋转罗盘相连,他的主要的功能就是使滑块有很好的摩擦性能。另一部分是由抗腐蚀的合金材料制成的鞋,它的主要功能是使滑块在活塞的球形头上摩擦。这个结构能够很好的利用金属的展延性和高分子材料的摩擦性。 (见图 2)在滑块上的主要的静力在图 3 中有表示。滑块上的力 F 来自活塞头,包括活塞尾端的液体压力 Fp,反弹力 Fs, 活塞和滑块的惯性力 Fa,还有活塞与圆孔之间的摩擦力 Ff。 来自旋转罗盘的反作用力 N 能够被分成两部分液压轴承力 Nh 和机械表面压力Nm,如下所示:N=Nh+NmN 和 F 的关系是: F=Ncos5.结论根据作者的研究,一些关于滑块在自然水润滑下的材料选择和结构设计结论可以总结为如下几条:(1) 用高分子材料制作成的滑块与用抗腐蚀性合金制成的旋转罗盘结合有很好的摩擦性。(2) 在滑块的大量制造中棉布纤维填充的酚醛塑料被使用,目的是使工作压力低于 14MPa。(3) 在滑块上的反弹力应该足够强以确保滑块和旋转罗盘表面上的连接压力在0.10.2MPa。除此之外还有一些实验需要进行,并且拥有良好韧性的陶瓷材料也会被引进用来大量制造滑块和旋转罗盘。在滑块研究上的经验将会为自然水液压轴向活塞泵和电动机的设计和发展提供很大的帮助。参考文献:1 Joseph L. Foszcz, Hydraulic Fluid Choices, Plant Engineering, (8),1996,68.2Li Zhuangyun, et al, Development of Hydraulic Pump to Operate with Raw water, Proceedings of ASME Fluid Engineering Division Summer Meeting, Washington DC, USA, June 21-25,1998.4吴仁荣,水润滑滑动轴承的设计计算,机电设备, (6) ,1997,30.5许耀铭,油膜理论与液压泵和马达的摩擦副设计,北京;机械工业出版社,1987.
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