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1047 起重 夹钳 设备 总体 设计

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1047-起重夹钳设备的总体设计,1047,起重,夹钳,设备,总体,设计

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毕业设计开题报告课题名称： 滑移式起重夹钳设备的总体设计 学生姓名： 方继松 院 别： 机械工程学院 专 业： 机械设计制造及其自动化 指导教师： 刘 伟 香 2011 年 3 月 1 日一、综述国内外对本课题的研究动态，说明选题的依据和意义：国内外对本课题的研究动态：夹钳作为一种起重作业机具被广泛应用于冷、热轧薄板厂，用来搬运各种半成品及成品钢卷，是一种工作效率很高、适应性极强、用途非常广泛的起重设备，属于冶金行业中的特种设备。按夹钳在夹持物料的过程中有无辅助外力，可将其分为外力辅助式夹钳和重力式夹钳。外力辅助式央钳是靠辅助外力实现对物料的夹持，不管货物的尺寸如何，只要辅助设备工作得当，这种夹钳就能轻易地对其实现夹紧，它具有操作简单、生产效率高、夹持力可调等特点。相对于外力辅助式夹钳，重力式夹钳只能靠夹钳和物料的自重实现对物料的夹持，它具有安全可靠、结构简单、制造方便、成本低廉、不消耗动力能源、寿命较长等特点，因此得到了广泛的应用。目前我国应用较多的是重力式夹钳，由于其初始夹紧力的产生是靠夹钳和物料的自重实现的，如何用合适的力夹取物料，做到既能安全实现夹取，又避免钳体的受力太大而导致钳臂或物料的破坏就显得非常重要了。以带卷夹钳为例，如果钳口产生的夹持力不够大，夹钳夹持带卷就不可靠；如果产生的夹持力太大，钳臂的受力会很大，各钳臂的强度也会要求很高，导致钳体笨重：而且在夹持高温带卷时，夹持力太大时带卷接触面容易出现较大的塑性变形，而使其表面产生较深的压痕，破坏了带卷表面的完整性，给它的进一步加工带来不必要的麻烦。德国、美国、俄罗斯等国家，在央钳的研究方面做得很好，这些国家很早就对各种钳式取物装置进行了理论和实验研究。在我国，在吊夹装置、液压钢卷夹钳、重力式板坯夹钳、电动平移式板坯夹钳等方面进行过研究性工作。相对于国外，我们国家在夹钳上的研究还是非常有限，特别是在重力式带卷夹钳上，很少进行系统性的研究。选题的依据和意义我国目前的现役重力式带卷兴钳，一部分来源于原装进口，另一部分则是靠对国外同类产品的测绘仿制。由于缺乏对原装进口样机的深入性研究，事实上并没有真正消化吸收国外的相关技术，整个带卷夹钳的生产仍然处于仿制阶段。二、研究的基本内容，拟解决的主要问题：研究的基本内容:1.了解国内外起重夹钳技术的发展及应用情况、夹钳装置的工作原理，进行常用夹钳装置的结构分类与分析。2.确定起重机设计方案夹钳装置的设计、传动装置方案的设计以及对设备的稳定性进行分析。拟解决的主要问题:通过了解学习掌握夹钳装置的工作原理，对起重夹钳装置的结构进行分类与分析，通过分析从而确定起重机设计方案夹钳装置的设计，传动装置方案的设计以及分析设备的稳定性。三、研究的步骤、方法、措施及进度安排：研究的步骤、方法、措施先在导师的帮助下查阅相关的资料，通过收集资料对课题进行初步的了解，在理清夹钳装置的工作原理之后对其结构进行分析，确定总体方案，然后确定传动装置方案的设计和分析稳定性，最后通过分析设计模拟制作夹钳设备，通过实践看是否设计合理。进度安排序号各阶段完成的内容完成时间1熟悉课题及基础资料第一周2了解原理、翻译以及开题报告第二四周3确定起重机设计方案第五六周4夹钳装置的设计;传动装置方案的设计；设备稳定性分析;毕业设计中期检查第七八周5绘制CAD图和叫论文初稿第九十周6制作夹钳设备第十一十二周7整理设计说明书，交毕业设计完成稿第十三十四周8交毕业设计答辩申请暨资格审查表，答辩第十五周四、主要参考文献：1吴宗泽,罗圣国.机械设计课程设计手册M.北京:高等教育出版社，2007.2曹自立. 60t板坯夹钳搬运起重机试制成功J. 起重运输机械, 1996,(9):15-17. 3 谢华,郗江云,李建红.装配设计M. 北京：机械工业出版社,2007.4倪泽娅. 重力式板坯夹钳的开发与研制J. 重型机械科技, 2006. 5 马保生. 夹钳起重机的夹钳装置J. 太原重型机械研完所，2009.6贾和平. 25112t电动平移式板坯夹钳起重机太远J. 太原重型机械(集团)有限公司设计研究院，2009.五、指导教师意见：资料搜索较全面，准备充分，可以开题。签名： 六、教研室意见：签名： 注：此表由学生本人填写，一式三份，一份留系里存档，指导教师和学生本人各保存一份。毕业设计（论文）任务书课题名称：滑移式起重夹钳设备的总体设计 学生姓名： 方继松 院 别：机械工程学院 专 业：机械设计制造及其自动化 指导教师：谭湘夫 2010年12月1日1、主题词、关键词：滑移式起重机方案设计;传动装置方案的设计计算; 夹钳装置的设计;设备稳定性分析 2、毕业设计（论文）内容要求：(1) 查阅文献资料, 其中中文文献不得少于15篇，外文文献不少于3篇，将其中一篇外文文献（不少于3000英文单词）翻译成中文（将中英文装订在一起）。写出国内外起重夹钳技术的发展及应用情况、夹钳装置的工作原理、夹钳装置的工作要求及性能(2) 确定起重机设计方案; 设计夹钳装置;传动装置方案的设计(3) 设备稳定性分析(4) 用铅笔绘起重运输设备总装配图一张(0#)，主要部件图两张；还要求用AUTOCAD将上述图绘出(5) 说明书的撰写要求认真、准确、条理清晰;文中引用的文献要依次编号，其序号用方括号括起，如1、2，置于右上角，文献内容必须严格按照引用的先后顺序依次在毕业设计论文的最后列出;文档运用 “word长篇文档排版技巧”，按学院毕业设计手册要求的格式与样式排版;用公式编辑器编辑公式;毕业设计说明书正文字数在1.5万字左右,交打印稿与电子稿3、文献查阅指引:1吴宗泽,罗圣国.机械设计课程设计手册M.北京:高等教育出版社，2007.2曹自立. 60t板坯夹钳搬运起重机试制成功J. 起重运输机械, 1996,(9):15-17. 3 谢华,郗江云,李建红.装配设计M. 北京：机械工业出版社,2007.4倪泽娅. 重力式板坯夹钳的开发与研制J. 重型机械科技, 2006, (2):14-17. 5 利用百度搜索工具查阅相关内容的最新进展6利用湖南理工学院图书馆电子阅览室查阅、 收集相关资料7一定要找到三篇与论文有关的英文原版参考文献，参考文献至少1篇其中外文文献不少于3篇，将一篇外文文献（不少于3000英文单词）翻译成中文4、毕业设计（论文）进度安排：第1周 实习;设计前准备工作，接受设计任务、收集资料（至少18篇参考文献）第2、4周 了解国内外起重夹钳技术的发展及应用情况、夹钳装置的工作原理；作好制作准备工作；将3000字的与本课题有关的英文文献译成中文；交毕业设计（论文）开题报告第5、6周 进行常用夹钳装置的结构分类与分析；确定起重机设计方案第7、8周 夹钳装置的设计;传动装置方案的设计；设备稳定性分析;毕业设计（论文）中期检查第9、10周用铅笔绘起重运输设备总装配图一张(0#)，主要部件图两张；还要求用AUTOCAD将上述图绘出；交论文初稿（纸质打印稿）第11、12周 制作夹钳设备第13、14周 整理设计说明书，交毕业设计完成稿（要交WORD文档和PDF文档两种格式的电子稿)；准备毕业答辩第15周 交毕业设计（论文）答辩申请暨资格审查表 ；毕业答辩教研室意见： 负责人签名： 注：本任务书一式三份，由指导教师填写，经教研室审批后一份下达给学生，一份交指导教师，一份留系里存档。 Url: http:/www.HydraulicsP /200 /Issue /Article/True/79457 / Your hydraulic system isnt complete without the right type of pressure sensors. From sub-sea to aerospace applications, hydraulics can be found in benign laboratories or harsh operating conditions prone to extreme temperatures, shock, vibration, electromagnetic interference (EMI), radio frequency interference (RFI), and pulsations. As electronic controls started to appear in early 1970s, a new control system term, electrohydraulics entered the industrial world. These early control systems started the industrial automation revolution. Over time, better sensing technologies and the availability of low cost microprocessors and controllers accelerated the growth of hydraulic controls. Today, pressure measurements play an important role in determining the health of hydraulic systems by means of overall performance, safety, and feedback. Depending upon the application, most modern hydraulic systems operate from 1000 to 10,000 psi; however there are some that may go as high as 60,000 psi. Pressure measurements can be accomplished with a simple on-off pressure switch or an electronic pressure sensor that offers a linear electronic output signal. Electronic pressure sensors are replacing pressure switches, due to their flexibility and performance; however, there are topics that must be addressed for performance and reliability in hydraulic applications. Pressure sensing technologies, sensor packaging, hydraulics transient protection, and EMI/RFI protection must be considered carefully for each application. Figure 1. A typical capacitance sensor contains both a fixed and a moving plate. Pressure sensing technologies The two main technologies for pressure sensing are capacitive and piezoresistive. Capacitive technology employs gap sensing by means of a capacitance change between two plates; one fixed and other moving, as shown in Figure 1. This capacitor is normally connected to a complex electronic circuit that will covert the capacitance to an output signal such as 1-5 V or 4-20 mA. Because the change of capacitance is in the range of 1 pico Farad to 1 femto Farad, the electronic circuitry is placed closely to the sensing plates, to minimize stray capacitance. This tends to limit the operating temperature of the sensor, as there is a short distance between the media and capacitor. If a metal or doped semiconductor is stretched or compressed, its resistance changes because of dimensional changes (length and cross-sectional area) and resistivity change (this latter property is called piezoresistance). Strain gauge technology is used to measure the change in length from L to L and resistance change from R to R. The strain sensitivity or gauge factor, G, can be calculated by: (R R) (L L) For metal strain gauges, the typical gauge factor is 2. These strainmeasuring devices are normally called strain gauges and come in different sizes. Figure 2 shows an outline of a bonded foil strain gauge. Bonded foil strain gauges are made from nickel chromium or nickel constantin material and typically have a Mylar insulator backing. This allows one to glue the gauge to a metallic or ceramic substrate. Thin film gauges, fabricated by sputtering metal on an insulated substrate, do not require any glue for bonding. In the early 1960s, semiconductor gauges were developed to offer higher gauge factors (from 55 to 200) with a smaller package size. Semiconductor gauges can be fabricated in two ways: the use of bulk silicon or germanium material that has been doped in either P-type such as boron or N-type material such as phosphorus to provide the electrical and thermal performances; ion implanting using P and N types of material together to form a P-N junction. These strain gauges are normally connected in a Wheatstone bridge configuration as shown in Figure 3 (four active arms are shown for maximum compensation) to provide a limited temperature compensation. For metal or thin film strain gauges, the output signal is 3mV/V with an operating strain of 1100 microstrain whereas semiconductor gauges will provide up to 50mV/V with 300 microstrain. Pressure sensor packaging Primary pressure sensor packaging is dependent upon the sensing technology and operating conditions of an application. Signal conditioning electronics and electrical interface can be considered as secondary issues as part of this discussion. Lets review some of these packages, benefits, and issues. Most low cost ceramic capacitive sensing elements employ a ceramic diaphragm made with an Alumina 96, machined pressure port, retainer ring, housing, and O-rings. The ceramic diaphragm is normally held to the pressure port by means of a primary O-ring. A secondary O-ring is used with the retaining ring on the opposite side to hold the ceramic diaphragm when pressure is applied. In this design, the media comes in contact with the ceramic diaphragm, primary Oring, and pressure port material. For low-pressure applications, the ceramic diaphragm tends to be large and thin. This has the potential for failure under high shock and vibration conditions. Ceramic sensors are used in industrial and off-road applications up to 1500 psi; however, the proof pressure (also known as the overload pressure) is restricted to 1.2 times the rated pressure. Today, this technology has limited use above 1500 psi, due to the availability of low cost strain gauge technologies with much better performance and longevity. In cyclic environments, the proof pressure rating must be reduced to same as operating pressure range to avoid failure of the O-ring seal. Since this design does not incorporate a hermetic seal, these sensors are not suitable for operation in ammonia, hydrogen, oil and gas production, hydraulics, oxygen service, and many other critical mild to harsh applications. The O-ring can be specified in a range of materials to deteragainst specific media attack that can cause system failure in certain abusive environments. Sensor manufacturers typically provide a list of O-ring materials such as Buna, Viton, and EPDM that can be specified by the customer. Since the metal foil strain gauges tend to be large, they are normally put on a beam or diaphragm prior to welding to a pressure port. Thin film sensors are smaller, but they also need to be welded to a pressure port. In both cases, the welds need to be deep enough so that they do not fail under normal and overload conditions operating above 2500 psi. Under high cyclic and pressure conditions, where the pressure pulsations can vary by 50% of the pressure sensor range, the sensor package design must incorporate a mechanism to make sure that the weld is under compression to avoid sensor failure. Because both metal foil and thin film technologies have low outputs at high operating strains (typically 1000 microstrain), the diaphragm material must be carefully selected so there is enough room for overpressure without sacrificing shift in sensor performance. Common diaphragm materials used in metal foil and thin film sensors tend to be 15-5, 17-4 and 17-7 PH high strength stainless steels with yield strengths up to 190,000 psi and low thermal coefficient of expansion. The pressure ports must be of the same material as the diaphragm to avoid any separation of the welds under thermal conditions. Sensors employing semiconductor strain gauge technology can be broken into two categories; oil-filled sensors employing a thin isolation diaphragm and ion implantation technology and the emerging diffusion bonded bulk silicon Krystal Bond Technology. Oil-filled piezoresistive sensors mainly employ a small silicon chip with ion implanted strain gauges, isolated from the real world by means of a thin metallic membrane (typical thicknesses between 0.001 and 0.0015 in., depending upon the pressure range). With bulk semiconductor strain gauge technology, the strain gauges are directly mounted onto a machined sensing element, where the diaphragm and pressure port are machined in the same process. This eliminates the problems associated with welds, oil filled cavities, and internal O-rings. The use of a direct inorganic diffusion process allows semiconductor gauges to be placed precisely on a metallic diaphragm efficiently and accurately on the side of the diaphragm that is not exposed to the media. The hermetic design is excellent for high cyclic environments associated with hydraulic pumps and motors. The high gauge factor, along with low operating strain, allows the diaphragm to be thick. This offers excellent proof and burst pressures. Figure 2. View of a typical bonded foil strain gauge. Figure 3. Semiconductor gauges use a Wheatstone bridge circuit. Pressure spikes and transient protection Rapid opening and closing of valves and solenoids in hydraulic systems tends to generate rapid, high frequency pressure spikes and transients that may last from a few microseconds to hundreds of milliseconds. The amplitude of these fast moving transients can be up to 20 times the rated pressure of a system, and will destroy electronic pressure sensors unless they are protected using snubbers and restrictors. These protection devices can be installed as an integral part of the sensor or as a stand-alone device. The devices, while protecting the sensor from damaging fast moving transients, can dampen the response time of the sensor (depending upon the design). Figure 4 shows details of integral and external pressure spike snubbing techniques. For system optimization, such as response time and snubbing, the length, L, and diameter, D, must be carefully selected. In an ideal condition, the snubber must be able to snub all signals that are between 100-150% of applied pressure to maintain fast throughput, but remains dependent upon the type of sensing technology and packaging. EMI/RFI protection In mobile hydraulic applications, electrical pollution in the form of fast electrical transients, Electro Static Discharge (ESD) and EMI/ RFI must be contained for system stability. Examples of this interference include communications equipment, switching power supplies, welding equipment, and electric motors. The sensor package must not generate or be influenced by unwanted external electrical signals from 100 kHz to 2 GHz. It must also be able to withstand radiated and conducted susceptibility and operated within its published specs in critical applications such as mobile cranes, scissor jacks, forklifts and many others. Typical protection used can be seen in Figure 5. Figure 4. Snubbers can use internal or external techniques to minimize pressures spikes. Figure 5. Typical EMC, ESD, and electrical fast transient protection scheme in pressure sensors. The danger of pressure spikes Pressure spikes are microsecond to millisecond bursts of pressure that can reach 15 times the normal system operating pressure. For example, if a valve shifts abruptly to block flow, a shock wave can be generated within the system. Likewise, if a hydraulic system is moving a load and the load suddenly stops, the system may react with a brief surge of pressure. System control electronics such as PLCs with millisecond scan times are not fast enough to detect spikes of such short duration. Often, the first indication that a system is generating pressure spikes is a positive shift in a pressure transducers zero output. System control electronics commonly indicate the shift in transducer output as a pressure out-of-range condition, which could cause the system controller to shut down. Pressure transducers are the components most vulnerable to damage from pressure spikes. Transducers, with much quicker response, react to spikes and can show signs of having been over-pressurized. This is not because the transducer is less durable than the mechanical gauge it replaced. Actually, a transducer designed for severe service should have been specified. Spikes