绿化洒水车设计(三吨载重量)管路设计和喷洒部件设计[CAD高清图纸和说明书]
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I 绿化洒水车设计(三吨载重量)管路设计 和喷洒部件设计 摘 要 绿化洒水车具有除尘、清洁路面、植被和降温等作用,是城市绿化建设和卫生建 设的专用汽车,随着人们对环境要求的不断提高,具有良好的市场前景。 这次设计的绿化洒水车(三吨载重) ,是在选择通用二类底盘的基础上,对它作了 一些改动。在设计中,主要完成了变速箱总成的改动,取力器总成的设计、水管总成 的设计、水箱总成的设计和各总成的位置布置,而且保证了改动后的洒水车具有良好 的动力性、操纵稳定性和行驶平稳性。 洒水车最典型的部分也就是洒水管路,这次设计的洒水车管路在设计方面与以往 不同的是各个管路在开关阀的作用下工作,不会影响各自管路的功能,使水泵在有效 的工作环境中发挥有效的功能,洒水车工作方式是,水罐的水从出水管经过水管阀门 与水泵进口相连,水泵出水口通过各水管阀门与各自的分水管相连,最后通过各喷洒 系统,实现不同的的洒水功能。洒水面在原来的基础上更能体现不同,水泡总成减轻 了重量,而喷射距离在同工况下更优越。 关键词:洒水车,管路,喷洒部件,设计 DESIGN OF PIPELINE AND SPRAY COMPONENTS OF GREENING SPRINKLER (3 TONS LOAD) II ABSTRACT Greening Sprinkler is used to dust, clean road, vegetation and cooling. Greening sprinkler is special purpose vehicle which is used for city building and health building.Because people need a good environment, it has good market prospects. The design for greening sprinkler (three tons load) is choosed a common chassis which is made some changes. In the design, the main designs are gearbox assemblys changes, tank assemblys design and the location of the assembly layout; it has also ensured that the changes for sprinkler have good momentum, handling, stability and smoothness of ride. The water spray pipeline is one of the most typical parts of greening sprinkler. The design of water spray vehicle pipeline in the design aspect is different with former that. Under the switch valve function, the pipelines cannot affect each other. The working mode of watering machine is that water flows from the water outlet pipes valves and pumps connect imports, pump through the outlet pipe valves and their respective sub-mains connected by the end of the sprinkler system. The water spray surface can manifest differently in the original foundation, and the blister unit can reduce the weight, but spray is away from under the same operating mode to be again more superior. KEY WORDS: sprinkler, pipeline, spraying components, design 目 录 第一章 前言1 第二章 洒水车总体设计3 2.1 洒水车总体概述3 2.2 洒水车总体设计3 2.3 洒水车的使用技术8 第三章 变速器改装与设计9 3.1 、档传动比的确定9 III 3.2 、档齿轮齿数的确定10 第四章 取力器的设计.13 4.1 取力器工作原理.13 4.2 取力器设计计算.14 第五章 管路设计.17 5.1 管路系统结构设计及工作方式.17 5.2 管路系统主要参数计算.18 5.3 液体阻力损失计算.19 第六章 水灌的设计.22 6.1 水罐及其附属构件的设计. .22 6.2 水罐盖的设计. .24 6.3 水箱附属结构的设计.25 第七章 主车架的改装.26 7.1 主车架强度校核.27 7.2 车架联接螺栓的校核.29 第八章 结论32 参考文献33 致谢34 Engineering Failure Analysis 14 (2007) 895902Failure investigation of a tie rod end of an automobile steering systemA.H. Falah *, M.A. Alfares, A.H. ElkholyMechanical Engineering Department, Kuwait University,P.O. Box 5969, Safat 13060, KuwaitReceived 30 May 2006; accepted 19 November 2006AbstractA failure analysis of a tie rod end of a sports utility vehicle (SUV) steering mechanism has been carried out in this study. The tie rod end is composed of two parts fitted together: a threaded part and an embracing part. Failure took place in the threaded part which is made of AISI 8620 steel. The vehicle had been in service for approximately two years and accumulated less than 30,000 km. An evaluation of the failed part was undertaken to determine the cause of failure and assess its integrity. Visual examination, photo documentation, chemical analysis, hardness measurement, and metallographic examination were all conducted. The failure surface was examined with the help of a scanning electron microscope (SEM) equipped with EDAX facility that determines chemical composition at desired locations within the part. Results indicated that the tie rod end had failed by fatigue with a crack initiation at the throat (minimum) area of the threaded part due to material deficiency and improper heat treatment.Keywords: Fatigue; Crack initiation/propagation; Material property1. IntroductionTie rods connect the center link to the steering knuckle on automobiles with conventional suspension systems and recirculating ball steering gears, Fig. 1. On automobiles with MacPherson strut suspension and rack- and -pinion steering gears, tie rods connect the end of the rack to the steering knuckle, Fig. 2. A tie rod consists of an inner and an outer end as shown in both previous figures.Tie rods transmit force from the steering center link or the rack gear to the steering knuckle, causing the wheels to turn. The outer tie rod end connects with an adjusting sleeve, which allows the length of the tie rod to be adjust -able. This adjustment is used to set a vehicles toes, a critical alignment angle, sometimes referred to as the caster and camber angles.Fig. 1. Conventional suspension.Fig. 2. McPherson suspension with rack and pinion.A vehicles steering and suspension systems should be checked regularly, at least once a year along with a complete wheel alignment. A worn tie rod end, due to rubbing and wearing, can cause wandering, erratic steering and excessive tire wear. If tie rod replacement is necessary, a wheel alignment is also required because tie rod replacement disturbs the toe setting.Tie rods may fail in many different ways, and except for a slight increase in noise level and vibration, there is often no indication of difficulty until total failure occurs. In general, each type of failure leaves characteristicclues, and detailed examination often yields enough information to establish the cause of failure. The general types of tie rod failure modes include fatigue, impact fracture, wear and stress rupture 1. Several causes of tierod end failure have been identified. These include poor design, incorrect assembly, overloads, inadvertent stress raisers or subsurface defects in critical areas, use of incorrect materials and/or manufacture process,and improper heat treatment 2. Tie rods in automobile suspension are generally robust and reliable components .However, problems do occur particularly due to manufacture error or driver misuse 3. The case under investigation involves failure of the outer part of an automobile tie rod. It was brought for analysis by the investigation bureau of the Ministry of Interior over a legal dispute between the driver of an SUV and a local car dealer who sold him the vehicle. The vehicle was driven for nearly two years and had registered less than 30,000 km. The driver claimed that while he was driving the vehicle, a sudden bang was heard and he lost control of the vehicle and hit the median rail guard of the highway. The vehicle was damaged and the driver, though still conscious, was slightly injured. He believed that there was something went suddenly wrong with a mechanical component of the vehicle and that caused the accident. The local car dealer, on the other hand, disagreed with the drivers scenario on grounds that the manufacturer produced thousands of such vehicles every year and they were, and still are, running fine all over the world without any reported serious failure. The dealer attributed the accident to careless driving behavior that resulted in a loss of control over the vehicle, which in turn hit the guard rail and led to vehicle damage. To settle the dispute, it was decided to undertake a thorough failure analysis investigation of all components of the steering mechanism to determine the cause of failure. All steering components were found intact though badly bent, except for the outer tie rod end which was fractured at the throated area of its threaded part. The embracing part of the outer tie rod end, however, was intact, except for two scars at its rim that could have happened when the threaded part broke into two pieces. The general appearance of the parts of the failed tie rod end is shown in Fig. 3a, where the two fragmented pieces of the threaded part were brought together to show how the tie rod end appeared before failure. Fig. 3b shows the two fractured parts separated. Fig. 4 gives the visual appearance of the embracing part and one fragment of the threaded part, both facing up. It is clear that fracture took place at the throat area of the threaded part where stress is expected to be high due to reduced cross sectional area and stress concentration. Further examination of the threaded part was conducted to determine the exact cause of failure.Fig. 3. Parts of fractured tie rod end (a) assembled and (b) separated.Fig. 4. Threaded part fracture surface and rim scars on embracing part.2. Experimental procedureThe failed threaded part of the tie rod end was inspected visually and macroscopically taking care to avoid damage of fractured surface. The failed threaded part of the tie rod end was ultrasonically cleaned prior to microscopic examination, photo documentation, chemical analysis and hardness measurement at the fracture surface and away from it. Scanning electron microscope (SEM) equipped with EDAX facility and an opticalmicroscope were both used in the investigation.3. Results and discussionChemical analysis using atomic absorption spectrophotometry was carried out at several locations of the failed threaded part of the tie rod end and the average values of the test results are given in Table 1 along with the specified chemical composition. Spectrum analysis revealed that the threaded part material was AISI 8620 steel which is usually used for main automobile steering components. The low percentage of manganese and ofchromium in the tested sample suggests that the final hardness of the part would be substantially reduced. On the other hand, the high percentage of nickel in the tested sample would result in lower toughness therebycompromising the mechanical property that is required to withstand impact loads resulting from bumpy roads. The surface hardness of the fractured tie rod end was measured to be 45.6 HRC. This suggests that the tie rod was not hardened properly, since hardness of tie rods, in general, is expected in the range of fifties for such applications. Table 1Chemical composition of failed threaded part of tie rod end and AISI 8620 steelFig. 5. SEM micrograph showing crack propagation region.It is evident from Fig. 4 that there exist two distinct areas on the fracture surface; one is smooth while the other is relatively rough. This is a typical fatigue fracture where crack originates at the edge of the smooth areaand propagates towards the rough area, which represents final failure. On the other hand, the smooth area of the fracture surface is dominant as seen in Fig. 4. This indicates that the tie rod end took some time to break from the instant of crack initiation till complete fracture; i.e. a high cycle fatigue failure case. This proves that the cause of the SUV accident was a lack of strength and low resistance to impact loads in the material of the threaded part of the tie rod end that initiated a crack and then took some time to reach complete separation. A specimen from the fractured surface was metallographically prepared and observed in a scanning electron microscope (SEM). Significant fatigue cracks were observed at the smooth area of the fracture surface. Theorigin of cracks was at the edge of the smooth area of the threaded part throat, suggesting that the stresses were highest at this region. Fig. 5 shows crack propagation on the fracture surface. Beach marks can be observed clearly which is a typical feature of fatigue failure 4. The origin of the crack was surrounded by beach marks. Also, the fracture surface at the fatigue region had a smooth appearance with a rippled beach mark pattern which indicates that fatigue had initiated at one point of the circumference and then grown across the fracture area. A small area has a rough, jagged look where the last portion of the throat broke away. No corrosion media were found on fracture surfaces. Fig. 6. SEM micrograph showing typical brittle fracture observed in final stage of crack propagation zone. Brittle fracture was observed in the final stage at crack propaga tion as seen in Fig. 6. Fig. 7 shows the micrography of the rough area of the fracture surface where variation of grain size combined with shallow dimples is evident. The light lines surrounding the grains in the figure indicate intergranular cracking that is usually observed with brittle fracture. A close-up of such grains revealed both intergranular and transgranular cracking at some locations as shown in Fig. 8.Fig. 7. SEM micrograph of the last portion of fracture surface to break away.Fig. 8. Close-up showing both intergranular and transgranular cracking.Quantitative chemical analysis was carried out by EDAX attached to SEM on the fracture surface to verify the presence of any other associated components. No presence of any detrimental foreign elements was observed.Metallographic view of a sample cut from the threaded part after polishing and etching with 2% Nital solution is shown in Fig. 9. As shown, the microstructure consists of pearlite (finger print appearance) and ferrite (which appears dark). This is typical of unhardened low carbon steel. No abnormality was observed in the microstructure.From the above observation, it can be ascertained that failure was caused by high stress concentration at the throat area mainly due to inadequate chemical composition which contributed to reduction in material strength and lack of toughness. Under the cyclic loading produced from driving the SUV on regular and bumpy roads, fatigue cracks had initiated at these stress concentration points, namely the throat, leading to fracture of the part at the instant when the local stress exceeded the material strength. It should be mentioned, as well, that every so often, the increased noise and vibration due to crack propagation go unnoticed till failure unexpectedly occurs. In order to further improve the durability of the tie rod end to stand the applied loads, it is suggested to increase the cross-sectional area of the threaded part throat and to enlarge the fillet radius.Fig. 9. Micrograph of thread part showing Pearlite (Finger prints Matrix) and aFerrite (sample was etched with 2% Nital).4. ConclusionThis study was conducted on a failed tie rod end of a SUV. Spectrum analysis and hardness measurement revealed that the failed part was AISI 8620 steel. The composition and hardness did not conform to the specified standard. Fractographic features indicated that fatigue was the main cause of failure of the tie rod end. On the fracture surface of the threaded part of the rod, the crack initiation region and beach marks could be clearly identified. It was observed that the fatigue crack originated from destructive areas in the vicinity of the throat and propagated from there. Failure analysis results indicate that the primary cause of failure of the tie rod was likely material deficiency. Formation of the crack initiation and propagation together with a final rupture within the fractured area supported this hypothesis and are, thus, in agreement with the claim of the SUV driver that the accident took place as a result of incompatible mechanical part, in this instance, the tie-rod end.References1 Sheldon GL. Unusual Failure of an automobile steering component, In: Failure prevention and reliability conference, Dearborn,Mich., USA, 1983; p. 2731.2 Kim HR, Seo MG, Bae WB. A study of the manufacturing of tie-rod ends with casting/forging process. J Mater Processing Technol2002;125126:4716.3 Sidders PA. Linked mulhead machines for operations on tie-rod ends. Mach Prod Eng 1970;30(December). p. 105462.4 Fatigue and fracture. ASM handbook, Metals Park (OH): American Society for Metals, 1996, vol. 19.Engineering Failure Analysis 14 (2007) 895902某汽车操纵系统的转向横拉杆故障研究A.H. Falah *, M.A. Alfares, A.H. ElkholyMechanical Engineering Department, Kuwait University,P.O. Box 5969, Safat 13060, Kuwait收稿日期:2006.5.30刊登日期:2006.11.19摘要:本论文对运动功能型车(SUV)转向横拉杆末端操控机制进行了故障分析,其中转向横拉杆末端由两部分组成:即螺纹连接组件和抱合杆组件。我们研究的这个SUV是行使了大约两年,总里程3万公里,其螺纹组件的成分是美国钢铁学会规定的8620号钢,故障就是在这个地方发生的。本论文采取了多种方法对故障部分进行评测,从而确定其发生原因并评定其故障后的完整性,其中有可视化检测、图像文件系统、化学分析、硬度测试和金相检验。通过带EDAX(能量弥散X线分析仪)装置的电子扫描显微镜(SEM)可以检测故障表面的任意部位的化学成分。结论指出如果螺纹组件的材料性能不好且处于不合适的热环境下,其结合处的一个初始裂缝会因疲劳效应导致转向横拉杆末端的故障。关键词:疲劳效应 初始裂缝/裂缝蔓延 材料特性1. 引言配备普通悬架系统和循环滚珠式转向装置的汽车,其转向横拉杆将中连杆和转向关节连接起来,如图1。配备MacPherson型支柱悬架系统和带齿条齿轮转向装置的汽车,其转向横拉杆将齿条和转向关节连接起来,如图2。而转向横拉杆如图1、2所示分为内端和外端。转向横拉杆将来自转向中连杆或齿条的力传向转向关节,从而使车轮转动。转向横拉杆的外端连接一个调节套以伸缩拉杆的长度,这样就可以调整汽车的车轮前端的角度,有时用来调整其转向节销的后倾角或外倾角。汽车的转向和悬挂系统应该定期地检查,一年至少进行一次全面的前轮校正。一个使用超期转向横拉杆,由于摩擦和磨损作用,会导致行车方向控制的不稳定和轮胎额外的磨损。如果需要更换转向横拉杆,那么相应地也要进行前轮校正,因为前者的更换会影响后者的定位。图1 普通悬架系统图2 带齿条齿轮的MacPherson悬架系统 转向横拉杆可能会有很多故障,但它除了在噪声等级和振动的少许增加上有所体现外,在其他方面常常没有故障的明显现象,除非横拉杆的所有的故障都发生了。通常情况下,每种故障都会有自己的特征迹象,如果经过详细的检查一般都会得到足够的信息来判断故障原因。转向横拉杆的故障类型常见的有:疲劳老化、冲击破坏、磨损和断裂1。其故障原因有一些已经得到了确认,包括设计缺陷、不合理的装配、超载、不固定的应力源、严酷环境下的隐患、材料使用错误、缺乏严格的制造过程和非正常受热2。一般说来,汽车悬架的转向横拉杆要能提供足够的扭矩和保持良好的可靠性。但是,故障还是时常发生,尤其是因为制造上的问题和不正确的驾驶方式3。本论文所研究的情况针对某辆汽车转向横拉杆的外侧连接部分的故障。这个故障引发了一名SUV司机和卖给他汽车的供应商的一场官司,内政部的调查局也对转向横拉杆的故障进行了调查分析。汽车已经行驶了将近两年,行程还不到3万公里。这名司机原告陈述说当他正在驾驶汽车的时候,突然听到一声巨响,然后汽车就失去了控制并撞到了公路中间的隔离护栏。汽车被撞坏,司机受到一些轻伤。他认为导致事故的原因是这辆汽车的机械部件突然出现了问题,。可是,汽车销售商认为完全不是这样的,他的理由是汽车制造商每年都生产大量的此型号的汽车,可是从来没有接到如此严重故障的报告。汽车销售商认为是司机的不正确驾驶导致了汽车的失控,这样才造成了汽车撞上护栏并损坏。为了解决这个官司,就必须要对汽车操纵装置进行全面彻底的调查分析,确定故障原因。所有现场散落的操纵部件都被收集起来,它们虽然扭曲的比较严重,但是都很完整。只有转向横拉杆末端螺纹连接头部分断裂,但是横拉杆连接端的抱合杆部分除了有一些划痕之外仍然完好。转向横拉杆的故障部分的照片如图3a所示,这里将螺纹连接头断裂的两部分拼接起来,复现转向横拉杆故障之前的形状。图3b是断裂的两部分各自的状态。图3 转向横拉杆断裂部件 a) 拼接后的组合 b)各自独立图4显示了抱合杆部分以及螺纹杆的断裂面朝上放置的照片。从这里可以很清楚的看到断裂是在螺纹杆的连接头部分发生的。因为这里横截面积太小并且是应力集中的地方,显然裂纹要在这里发生。需要对螺纹杆进一步地检查来确定故障原因。图4 螺纹杆的断裂面和抱合杆边缘的划痕2.实验流程 通过肉眼检查转向横拉杆发生故障的螺纹杆部分,并要避免对断面的破坏。然后对其进行超声波清洗,再采取金相试验,图像分析处理、化学分析,最后在断面的近端和远端进行硬度测量。在调查中使用了装备EDAX的电子扫描显微镜和光学显微镜。3.分析结果和讨论 取故障螺纹杆的几个部位,使用原子吸收分光光度测定法进行化学分析,在表1处给出了测试结果的平均值,同时给出了明确的化学成分。经过光谱分析显示出螺纹杆的材料是AISI 8620号钢,这种钢普遍应用于汽车操纵组件的主体部分。测试样本显示锰和铬的含量较低,这样这部分组件的硬度就大大地减小了。同时,高含量的镍将会使组件的硬度大大提高,从而使其机械性能中和,这样就能承受住崎岖道路颠簸的冲击力。测量显示转向横拉杆断裂表面的硬度是45.6 HRC。这说明转向横拉杆的硬度还不够,因为一般在这种应用环境下,其硬度应该是50 HRC。由图4可以证明,断裂表面存在两种截然不同的区域:一种是光滑的,而另一种相对粗糙。这是典型的疲劳断裂,即从光滑区域边缘首先产生裂纹,然后向粗糙部位蔓延,这导致了最终的故障。另一方面,由图4可以看出,断裂面大部分都是光滑区域。这说明转向横拉杆疲劳裂纹的延伸持续了很长时间,直到最后的故障发生。这是一个高周疲劳的典型案例。因此,SUV发生故障是转向横拉杆的螺纹杆的材料缺乏刚性,抵抗冲击的能力较弱造成的,从而螺纹杆产生了一个初始的裂纹,经过一段时间之后就导致了断裂。对断裂面样本经过金相处理,然后利用扫描电子显微镜观察,在断裂表面的光滑区域发现了典型的疲劳裂纹,其源头在区域的边缘,表明了这个源头所承受的压力是最大的。图5展示了断裂表面的裂纹蔓延过程,从中可以很清楚的看到海滩状条纹,这是疲劳故障的典型特性4。表1 转向横拉杆产生故障的螺纹杆和AISI 8260号钢的化学成分图5 SEM(电子扫描显微镜)显示裂纹延伸区域的微观图像 疲劳区域的断裂表面是光滑的,中间带有海滩条纹,围绕着裂纹源头。这证明了疲劳裂缝最初是一个点,然后就慢慢延伸,形成断裂面。另外一小部分区域是粗糙的,呈锯齿状,螺纹杆最后断裂就是在这里发生的,并且在断裂面没有发现腐蚀现象。 图6所示的是在裂缝延伸的最终区域的脆性断裂。图7是断裂面粗糙区域的微观图像,其中有一块块的颗粒周围形成了薄薄的一层涟漪。图中发亮的线条围绕着若干块状颗粒,这是脆性断裂产生的晶间裂纹。图8特写了一些块状颗粒的晶体间和晶体内的裂纹。 在断裂面上用带EDAX的电子扫描显微镜进行化学定量分析,以查明是否还有其他相关的成分。结果发现没有其他的引起故障的因素。图6 裂缝延伸的最终区域所观察到的典型脆性断裂的SEM图像图7 导致部件分离的最终断裂面SEM图像图9是螺纹杆样本切片的金相学照片,样本已经过了抛光和2的尼特溶液的蚀刻处理。其微观结构由珠光体(图中指纹状的图像)和铁酸盐(图中较黑的部分)组成。这是典型的未经过硬化的低碳钢。图9未发现微观结构的异常。通过以上的实验观察,可以确定故障是由施加在螺纹杆连接头的高应力造成的,主要原因是不合适的化学成分造成了材料的硬度不够,不能提供足够的力。在崎岖不平的路上驾驶SUV,汽车受到周期载荷,疲劳裂纹就是因这些应力集中点的冲击而形成的,也就是说,当应力超过材料的承受能力时,螺纹杆连接头就断裂了。有一点需要提及的是,裂纹蔓延造成的不断增加的噪声和震动常常不会引起人们的注意,直到故障意外地发生。为了进一步地改善转向横拉杆对外加负载的承受能力,建议增加螺纹杆连接头的横截面积并且扩大其圆角半径。图8 晶体间和晶体内裂缝的特写图像图9 由珠光体(指纹状阵列)和铁酸盐(用2Nital溶液蚀刻)处理过的螺纹杆微观图像4结论本论文研究点是基于SUV转向横拉杆的故障。光谱分析和硬度测量证明故障是由AISI 8620号钢造成的,其成分和硬度不符合规定的标准。金属断面在显微镜下的特征显示了转向横拉杆的故障是因为疲劳效应。在横拉杆的螺纹杆断裂面上,裂纹初始产生的地方和海滩状条纹清晰可辨。 观察到了疲劳裂纹从螺纹连接头附近被破坏的区域开始产生,并由此蔓延开来。故障分析结果显示出转向横拉杆故障的主要原因是材料的不符合标准。裂纹初始形成和延伸导致了连接头最终的断裂,并且证明了SUV司机的观点是正确的,即汽车故障发生的原因是机械部件转向横拉杆,不符合标准。参考文献1 Sheldon GL. Unusual Failure of an automobile steering component, In: Failure prevention and reliability conference, Dearborn,Mich., USA, 1983; p. 2731.2 Kim HR, Seo MG, Bae WB. A study of the manufacturing of tie-rod ends with casting/forging process. J Mater Processing Technol2002;125126:4716.3 Sidders PA. Linked mulhead machines for operations on tie-rod ends. Mach Prod Eng 1970;30(December). p. 105462.4 Fatigue and fracture. ASM handbook, Metals Park (OH): American Society for Metals, 1996, vol. 19.
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