1.5兆牛摆动剪切机构设计【全套CAD图纸和论文】
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译文轧制过程中的热传递一 热带轧制的温度变化板坯再加热到所要求的温度后进行轧制。一个典型的热带轧制工艺包括以下几个主要步骤：（1） 板坯轧制前用高压水除鳞系统除鳞，有时采用立辊轧机同时除鳞。（2） 粗轧成 1940mm 后的中间料。粗轧过程通常伴随立辊和道次间的除鳞操作。（3） 将中间料从粗轧机运至安装在精轧机前的飞剪处。飞剪用来剪切料头和料尾。（4） 中间料在进精轧机组前的除鳞。（5） 精轧至所要求的厚度。机架间可能进行除鳞，有时也可能进行带钢冷却。（6） 轧材在输出辊道上的空冷和水冷。（7） 轧材的卷取。在轧制工艺过程中，轧件向其周围物质进行各种热传递。一些损失的热量由轧件变形所产生的热予以弥补。热带轧制过程中，轧件温度降低和升高的主要因素通常可以区分如下：（1） 热辐射引起的温降。（2） 热对流引起的温降。（3） 水冷引起的温降。（4） 向工作辊和辊道热传递导引起的温降。（5） 力学加工和摩擦引起的温升。关于这些因素的分析简述如下。二热辐射引起的温降 采用两种方法进行热辐射引起的温降公式的推导。第一种方法忽略了材料内部的温度提督，利用斯蒂芬-玻尔兹曼定律计算辐射到环境中的热量为：q =S drdtTAar)(4式中 辐射体的表面积，m 2；rAq 从物体辐射的热量，J；drS斯蒂芬- 玻尔兹曼常数；T轧件在 t 时刻的温度，K;Ta环境温度，K；t时间，s；辐射系数。物体损失的热量由下式给定：q = drTcVr式中 c轧件质量热容， J/（kgK） ；Vr辐射体的体积，m 3轧件的密度，kg/m 3。考虑到热平衡条件 q = q 及式 1-1 和式 1-2，可以计算出温降速度 ar：drar= )(4arTcVAStT通常假设 TaT，并简化某些方程以达到协调形式，得出辐射温度差速度公式，总结见表 1-1 所示。在推导这些公式时，未考虑温度对参数 S、 、 及 c的影响。不过实际上这些常数随温度的变化可能都是很大的，所以，式 1-3 的最终形式将取决于这些常熟选择的平均值。辐射时间 tr 内的温降 可以通过对微分方程几分进行计算：rT= rtrda0第二种计算辐射引起温降的方法考虑到沿材料厚度方向上的热传递。若 z 是物体内部至其表面的距离，则从傅里叶公式可得： 2dzTat式中 a轧件的热扩散率， m2/s。微分方程 1-5 可以利用有限差分法进行数值求解。这些计算的目的是要建立一个影响轧制过程轧件平均温度 T 和可测量的轧件表平 均面温度 T 之间的关系。表 面三热对流引起的温降热带轧制时的对流传热与轧件周围空气的运动有关。这种运动不断地带入新的空气粒子与轧件接触。取决于该内部运动是强制的，还是自然的，将热传递区分为强制对流和自然对流。在热带轧制中通常出现后一种情形。在计算对流引起温降时的一个重要方面是确定传热系数。该系数取决于材料温度、环境温度、材料质量热融合密度以及空气流的动态粘度及其特性，即自然、强制层流或紊流等情况。对于此关系所得出的数学描述有很大争议，实际计算不宜采用。部分研究人员一致认为，对流引起的温降 应当表示为辐cvT射引起温降的莫以分数：= （ ） cvTkr这里， 是对流和辐射引起温降间的比率，根据不同的研究结果，其值在0.010.22 之间变化。四水冷引起温降若假定在轧件向冷却水传热石传导起着重要作用，就可以计算出水冷引起的温降。因此，当冷却沿轧件款度方向连续地接触其一侧表面时，通过轧件表面所传递的热量就可以用公式表示为：atTkbqww)(2 式中 k表层导热系数，W/（mK） ；通过轧件外表面所传递的热量，J；wb冷却水接触长度，m； 轧件宽度，m；Tw冷却水温度，K；tw冷却水接触时间，s 。由轧件释放的热量由下式给定：)( dwTcVq式中 V冷却水所冷却的轧件体积，m 3；水冷引起的温降，K。dT根据热平衡条件 ， ，式 1-7 和式 1-8，并考虑到：wqtw= vb式中 v轧件速度，m/s。和另一条件：hVb1我们得到水冷引起的温降为：= dTavbckw)(2冷却水所吸收的热量可以表示为：= wq)(wV式中 水的密度，kg/m 3；水的质量热容，J/（kgK） ；wcVw水的吸热体积，m 3；水的温升，K。T根据热平衡条件 = ，式 1-8、式 1-11 和式 1-12，并考虑到：wqhvdV式中 d带钢单位宽度上的水流量，m 3/（ms） 。我们得到下列冷却水温升公式：= wTabvThckw)(2式 1-11 并没有明确地给出温降与冷却水流速和压力的关系。然而，冷却水的流速和压力却大大地影响着隔开轧件于冷水的表面成的导热系数 k。事实上，表面层中包含有充当屏障作用的氧化铁皮和沸腾水。随着冷却水流速和压力的提高，该屏障作用将在很大程度上被削弱。五因工作辊热传到引起的温降如果假设两个初始稳定温度分别为 T 和 Tr 的物体相互挤压，并假设平面的界面处在又有氧化层的阻力，则可以计算出因工作辊热传导引起的温降。在作出上述这些假设之后，则可以用以下的热平衡方程进行过程的描述。根据沙科的研究，通过钢板的两个最晚层的总热量可以根据下式计算：atTkAqcrcc)(4 式中 Ac轧件和工作辊的接触面积， m2；k轧件氧化成的导热系数，W/（mK） ；由于热传递工作辊所获的热量或轧件所失去的热量，J ；cqTr轧辊温度，K；a轧件的热扩散率， m2/s。辊缝处轧件损失的热量由下式给定：)( ccTVq式中 轧件与工作辊接触而产生的温降，K 。T根据热平衡条件 = ，式 1-15 和式 1-16，并考虑到：cqvRtc及 achVA1式中 R轧辊半径，m；轧件平均厚度，m。a我们得出下列因工作辊热传导引起的温降公式：= cTavRhkra5.0)(4通过简化某些方程以达到协调形式，得出与辊接触引起的温降公式，总结见表 1-2，绘制成曲线如图 1-3 所示。不同的温降计算公式之间的显著差异主要是由于在预测导热系数 k 时的误差造成的，该系数之取决于轧辊和轧件件氧化层接触阻力的大小。原文Heat Transfer During the Rolling Process1.1WORKPIECE TEMPERATURE CHANGE IN HOT STRIP MILLAfter reheating a slab to a desired temperature, it is subjected to rolling. A rolling cycle in a typical hot strip mill includes the following main steps:1.Descaling of the slab prior to flat rolling by using high-pressure water descaling system in combination, in some cases, with edging.2.Rough rolling to a transfer bar thickness which may vary from 19 to 40 mm. The rough rolling is usually accompanied by edging and inter pass descaling.3.Transfer of the transfer bar from roughing mill to a flying shear installed ahesd of finishing mill. The shear is usually designed to cut both head and tail ends of the bar.4.Descaling of the transfer bar prior to entering the finishing mill.5.Finish rolling to a desired thickness with a possible use of interstand descaling and strip cooling.6.Air and water cooling of the rolled product on run-out table.7.Cliling of the rolled product.Various types of heat transfer from the rolled workpiece to its surrounding matter occur during the rolling cycle. Some of the lost heat is recovered by generating heat inside the workpiece during its deformation.The main components of the workpiece temperature loss and gain in hot strip mill are usually identified as follows:1.loss due to heat radiation,2.loss due to heat convection,3.loss due to water cooling,4.loss due to heat conduction to the work rolls and table rolls,5.gain due to mechanical work and friction.The analytical aspects of these components are briefly described below.1.2TEMPERATURE LOSS DUE TO TADIATIONTwo methods have been employed to derive equations for temperature loss due to radiation.In the first method, the temperature gradient within the material is assumed to be negligible. The amount of heat radiated to the environment is then calculated using the Stefan-Boltzmann law:q =S drdtTAar)(4Where surface area of body subjected to radiation, m2;rq amount of heat radiated by a body,J;rSStefan-Boltzmann constant;Ttemperature of rolled material at time,K;Taambient temperature,K;ttime,s;emissivity.The amount of heat lost by a body q is give by:drq = drTcVrWhere cspecific heart of rolled material, J/（kgK）;Vrvolume of body subjected to radiation, m3density of rolled material, kg/m3。The rate of temperature loss ar can be calculated by considering the heat balance condition q = q , and Eqs.1-1 and 1-2:dr ar= )(4arTcVASdtTEquations for the rate of temperature loss due to radiation which have been obtained by reducing some of the known equations to a compatible form with an assumption that TaT are summarized in Table 1-1. In the derivation of these equations, the dependency of the parameters S、 、 and c on temperature is not taken into account. However, the variations of these constants with temperature may be significant and,therefore, the final from of 1-3 will depend on the average values selected for these constants.The temperature loss during radiation time tr can be calculate by intergrating cTthe differential equation:= rTtrda0The second method of calculating temperature loss due to radiation takes into account the heat transfer along the thickness of the material. If z is the distance from the center of the body toward its surface, then from a Fourier equation we obtain:2dzTatWhere athermal diffusivity of rolled material ,m2/sThe differential equation 1-5 can be solved numerically by the method of finite differences.The goal of these calculations is to establish a relationship between the average temperature of the material Tave which would affect the rolling deformation process and the material surface temperature Tsurface which could be measured.1.3TEMPERTURE LOSS DUE TO CONVECTIONIn the hot strip mill, heat transfer by convection is related to the motion of air surrounding a workpiece. This motion continuously brings new particles of air into contact with the workpiece. Depending upon whether this internal motion is forced, or free, the heat transfer is referred to as either forced or free convection. The latter is a usual case in the hot strip mills.A key factor in the calculation of temperature losses due to convection is to determine the heat transfer coefficient, which depends on the material temperature, ambient temperature, material specific heat and density, and the dynamic viscosity of the air flow and its characteristic, i.e., free, enforced laminar, turbulent, etc. The known mathematical interpretations of this relationship are too controversial to be recommended for practical calculation. A consensus among some research workers is that the temperature loss due to convection should be expressed as a certain cvTpercentage of the temperature loss due to radiation:= （ ） cvTkrHere is the ratio between the temperature loss due to convection and radiation and varies between 0.01 and 0.22 according to different studies.1.4TEMPERATURE LOSS DUE TO WTER COOLINGThe temperature loss due to water cooling can be calculated by assuming that conduction plays a major role in heat transfer from a workpiece to water. Therefore, when water contacts one side of the workpiece continuously across its width, the amount of heat passing through the outer surface of the workpiece may be expressed by the formula:atTkbqww)(2 Where kthermal conductivity of the surface layer, W/（mK） ；amount of heat passing through outer surface of the workpiece,J;wqbwater contact length, m;wworkpiece width, m;Twwater temperature, K;twwater contact time,s.The amount of heat released by a workpiece is given by: )( dwTcVqWhere vvolume of workpiece cooled by the water,m3;temperature loss due to water cooling, K.dFrom the heat balance condition = ,Eqs.1-7 and 1-8, and taking into account that wqtw= vbwhere Vworkpiece velocity, m/sand hb1We obtain that the temperature loss due to water cooling is equal to = dTavbckw)(2The amount of heat absorbed by cooling water may be expressed as:= wq)(wVWhere density of water ，kg/m 3；specific heat of water，J/（kgK） ；wcVwvolume of water absorbing heat，m 3；From hert balance = , Eqs.1-8, 1-11, and 1-12, and also taking into account thatqwhvdwWhere dwater flow per unit of strip width, m3/（ ms）.We obtain the following formula for the temperature rise of water:= wTabvThckw)(2Equation 1-11 does not show an explicit dependence of the temperature loss on the flow rate and pressure of cooling water. The flow rate and pressure, however, may substantially affect the thermal conductivity k of the surface layer that separates the body of workpiece from cooling water. Indeed, the surface layer consists of scale and boiled water, which work as a thermal barrier. This barrier will be weakened to a greater degree with increase of both the flow rate and pressure of cooling water.1.5TEMPERATURE LOSS DUE TO CONDUCTION TO WORK ROLLSTemperature loss due to heat conduction to the work roll can be calculated if it is assumed that two bodies of uniform unitial temperature T and Tr are pressed against each other and that, at the interface, considered to be plane, there is contact resistance formed by oxide layer.Under these assumptions, the process can be described with the following heat balance equations. According to Schack, the total amount of heat passing through two outer surfaces of the plate may be calculated from the formulaatTkAqcrcc)(4 Where Accontact area between rolled material and work rolls，m 2；kthermal conductivity of the workpiece oxide layer，W/（m K） ；heat gained by work roll or heat lost by body due to thermal cqconduction，J；Trroll temperature，K；athermal diffusivity of workpiece，m 2/s。The amount of heat lost by the rolled metal in the roll bite is given by:)( ccTVqWhere temperature loss by rolled material due to contact with work rolls，K。From the heat balance condition = ，Eqs 1-15 and 1-16, and also taking cqinto account that vRtcand achVA1where Rwork roll radius, m.haaverage workpiece thickness, m.we obtain the following formula for the temperature loss due to conduction to work rolls:= cTavRhkra5.0)(4Equation for temperature loss due to contact with rolls which have been obtained by reducing some of the known equations to a compatible form are summarized in the Table 1.2 and are plotted in Fig.1.3. The substantial discrepancies in temperature losses calculated from different equations are due mainly to the uncertainty in estimating thermal conductivity k which depends on the contact resistance resistance of the oxide layer between the roll and the rolled material.700/500 型钢热连轧机设计指导书1 设计题目1.5 兆牛摆动剪切机的设计2 设计题目的目的和要求通过 1.5 兆牛摆动剪切机设计，使学生获得单体机械设备总体方案的选择方法，计算方法的合理应用提高绘图技术和设计能力。掌握设备的维修，润滑方法的知识和经济计算，了解设计中对控制系统的要求，提高收集，查阅资料和专业外语翻译能力。在老师指导下，独立完成单体机械设备 1.5 兆牛摆动剪切机设计，合理选用的计算公式，有据撰写设计说明书符合规范，绘出总图，部分零件图，图形正确清晰，图面符合标准，完成规定的专业外语翻译资料。3 设计原始参数机组参数原始断面 136 136 ，成品断面 90 90 ，原料速度 1.5m/s，成品速度2m2m5m/s，轧制温度 ，压下速度 1.2mm/s，压上速度 2.6mm/s，钢种：普碳低合金钢950oc摆动剪切机参数轧件运行速度 1.5m/s，剪切断面 136 136 ，剪切温度2oc剪切材质 钢#204 毕业设计过程的步骤4.1 进行现场调研，了解生产工艺过程，设备的作用，和生产中存在问题查阅有关资料和文献，写出绪论。4.2 对设计题目认真思考，综合论证提出合理的设计方案评述4.3 设计计算，撰写说明书，设计说明书符合规范并打印订装成册。4.4 计算机绘图，图面，线条符合标准，校准后打印。4.5 外文翻译，打印中文译稿，将译文，原文装订在设计说明书和附录中。4.6 评阅人评阅，交出设计说明书和图纸，由评阅人进行评阅。4.7 毕业答辩，写出毕业答辩申请书批准后按时参加毕业答辩。5 设计说明书基本内容1 绪论1.1 课题的选择的背景和目的1.2 热轧型钢的国内外的发展趋势1.2.1 轧机布置向半连续化或全连续化发展1.2.2 轧制工艺改革出现了切分轧制、热轧冷拔1.2.3 轧机结构改造 提高轧制速度1.2.4 加热炉控制1.2.5 冷却工艺改造1.3 剪切机的种类和用途1.3.1 摆动式剪切机1.3.2 滚动式飞剪1.3.3 曲柄偏心式飞剪1.4 摆动剪研究的内容和方法1.4.1 摆动剪在型钢连续机组布置和作用1.4.2 型钢热连轧机的生产工艺1.4.3 摆动剪的结构特点和研究的内容与方法2 摆动剪设计方案的选择和评述2.1 摆动式飞剪机设计方案的选择2.1.1 摆动式飞剪传动简图2.1.2 摆动剪的剪切过程2.2 摆动剪方案评述2.2.1 减小摆角2.2.2 增加许用摆角3 剪切力的计算3.1 剪切速度和剪切力3.1.1 摆动剪设计参数3.1.2 剪切机构主要参数的确定3.1.3 剪切速度的确定3.2 剪切力矩的计算4 电机型号及容量的选择5 主要零件的强度计算5.1 齿轮的强度计算5.1.1 按齿面接触强度设计5.1.2 计算5.1.3 按齿根弯曲强度设计5.1.4 几何尺寸计算5.2 曲轴的强度计算5.2.1 曲轴的尺寸和材料性能5.2.2 曲轴的强度校核5.3 切向键的计算5.4 滑块损坏的改进设计6 润滑方法的选择6.1 润滑和摩擦的概念6.2 轧钢设备润滑方法7 试车方法和对控制系统的要求7.1 试车要求7.2 维护规程8 设备的可靠性及经济分析结论致谢参考文献1何德誉.曲柄压力机M.北京：机械工业出版社，1982.62n.N 波卢欣等.金属与合金的塑性变形抗力M北京：机械工业出版社，1964.23北京钢铁学院.飞剪专辑C.北京.北京钢铁学院出版社，1982.64刘玉孚等.试论 1.5 兆牛摆式飞剪的改造C，19885王德春等.鞍钢二初轧摆式剪滑槽损坏原因的理论讨论H.鞍山钢铁学院，1990.3附录译文和外文 1.5 兆牛摆动剪切机构设计摘要1.5 兆牛摆动剪切机是安装在 500 型钢热连机前，用于切头切尾和卡钢事故的处理剪。随着国民经济的发展，对型钢产品数量的要求更高。本设计为型钢设计切头的摆动剪，设计中对摆动剪的局部做了改进。首先，本文讨论了型钢轧机在国民经济中的地位，并对 300/500 机组平面布置示意图的概况进行了整体的介绍。并介绍了摆动剪的结构特点和研究的内容与方法。根据现有设备状况，对设备生产中存在的问题进行分析，对主要部件结构做了合理的选用。然后，根据机组原始参数初选主电机容量，对其进行发热校核和过载校核，对主要零件进行强度校核。对齿轮做了强度计算，对曲轴计算了弯曲应力，弯扭合成应力；校核了危险断面；以及滑块损坏的改进设计及润滑方法，简单计算摆动剪的可靠性和经济评价。通过以上工作，1.5 兆牛摆动剪切机在使用寿命、产品质量理论上应该有一定的提高。设计内容有实际价值。该剪作为加热炉前方坯切头飞剪。关键词：剪切机，摆动，主传动 A Design of 1.5 Swing ScissorsMN1.5 swing scissors is installed before the 500 sharp steel of hot continuous rolling MNmills, which is used to cut the head and end of the steel and deal with the jamming of the steels.With the development of the national economy, the request of the sharp steelss quality is higher than before. In the thesis, the cutting of the head of the 1.5swing scissors is researched, and makes some improvments of partial strcture.NFirst, the thesis has discussed the position of the rolling mill of sharp steel in the national economy, and makes the general instruction for 300/500 unit plane arrangement. Next, introducing the structural characteristic of the swing cutting and the method and content of the research .According to exising equipment condition, analysing the exist problem in equipment production, the strcture of the major parts are reasonable to choosed. Then,according to the primitive parameter of the unit, I primarily choose the capacity
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