玻璃升降器外壳复合拉伸模的设计-冲压模具首次落料拉深【含12张CAD图纸、文档所见所得】
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学生实习报告（限 1500 字以上）院（系）：机械工程 专业：机械设计制造及其自动化 班级：0304 姓名：叶明飞一、实习的主要内容生产实习是机械类专业教学中的一项重要实践环节。其目的是使学生了解和掌握本专业基本生产实际知识，培养学生理论联系实际及初步的独立工作能力，为后续有关课程的学习打下基础。实习可分为两个阶段：第一阶段为见习实习；第二阶段为结合专业方向的生产实习。实习内容是使学生接触和了解机械制造的生产过程，学习到有关主要工种加工方法的基本知识，为学好金属工艺学、机械制造基础奠定必要的感性知识基础，同时也为学习其他技术基础课建立一些实践基础。 实习目的是使学生了解各类机械的运转和工作原理，并结合本专业的需要和目的，了解和观察本专业涉及到的各类机械的组成结构、运转机构和工作原理以及生产过程，为课程设计和毕业设计打下基础。结合专业方向的生产实习应根据专业特点，有针对性的到一些工矿企业单位进行。2006 年初我在衡阳冶金机械厂实习：1 参加由公司组织的理论知识的学习，由有经验的领导、工程师授课，学习公司的文化、以及公司的发展前景、主要产品的生产流程和必要的技术要求以及一些改进方向、公司必须保留和更新发展的技术核心等等。2 在有经验的师傅的指导下，亲自动手拆装模具、维修模具以及学习模具的结构组成以及工艺技术要求、模具的装拆的方法和技巧、同时也要求设计一些简单实用的模具，为以后设计或改进大型模具做准备。3 参加由公司有经验的技术员指导的模具设计，学习如何根据模具的用途设计一些实用的模具，以及设计制造模具时应该注意的主要问题和细节。二、实习取得的经验及收获毕业实习是一门专业实践课，是机械类各专业学生学习了各门专业课程之后，在进行毕业设计或毕业论文时必不可少的实践教学环节。它对于培养我们的动手能力有很大的意义，而且可以使我们了解传统的机械制造工艺和现代机械制造技术。我国现行的教育体制，使得通过高考而进入大学的大学生的动手实践能力比较薄弱。因此，处于学校和社会过渡阶段的大学就承担了培养学生实践能力的任务。毕业实习就是培养学生实践能力的有效途径。通过实习掌握了模具的一些基本知识，如模具的组成结构、如何根据用户的需要去设计一些简单的模具、在模具设计时的工艺、公差、粗造度、等如何选择和应用有了初步的理解。我们机械制造及自动化专业所学习的重点在于各种机械成型设备，本次实习就是为了让我们能够对于我们所学过的各种仪器、设备有一个感性的直观的认识，从而把书本上的理论和现实中的传统技术和已经被应用于实际的最新发展的高新技术联系与结合起来，进一步巩固和深化所学的理论知识，弥补以前单一理论教学的不足,为后续专业课学习和毕业设计打好基础。三、存在的不足及建议通过实习我本人感觉到还有很多不足的地方：1、专业知识还不是很扎实，特别是公差方面的，为了让设计出来的产品达到要求而一味的加大精度，给制造带来了难度；2、实际操作能力不够，现在是技术更新的时候，公司都引进了很多先进的生产设备，但自己对这些高新设备束手无策；3、初到公司缺乏工作经验，很多的工作感到无从下手，没有一个完整的头绪，很难单独去接受一个实际的课题。通过实习我想对学校一点建议：虽然自己只工作了两个月，但还是感觉到了学校和公司之间有很大的差距。如果能缩小这种差距的话，对以后学校就业将有很大优势，更对学生能够很快融入工作环境打下坚实的基础。我就以过来人的身份建议学校能够更加注重学生的实际动手能力，加强学生的实践能力的培养，如增加学生的在校实习的机会和延长学生的实践活动的时间，更加注重在老师的指导下让学生真正的参与到实践中去。毕业设计期间学校是否能考虑组织学生到生产现场去参观实习，让学生接受最为直接的设计基本知识，比凭空去设想更有效果。毕业设计说明书毕业设计说明书玻璃升降器复合拉伸模的设计玻璃升降器复合拉伸模的设计年 月 日目目 录录第 1 章 前言.1第 2 章 冲裁工艺设计.22.1 冲裁工艺计算.22.1.1 工艺力和功的计算.22.1.2 压力机的选择.42.2 模具总体设计.52.2.1 模具类型的确定.52.2.2 操作方式的确定.52.2.3 定位、联接型式的确定.52.2.4 模具压力中心的确定.62.2.5 模具精度的确定.62.2.6 模具闭合高度的初定.62.3 定位装置.62.4 卸料装置.72.4.1 卸料装置的选择.82.4.2 弹性元件的设计.82.5 落料凹凸模的设计.92.5.1 凸模结构的确定.92.5.2 凹模结构确定.102.5.3 凹凸模工作部分尺寸设计.102.5.4 凸凹模工作表面技术要求.122.5.5 凸凹模材料.122.6 导向装置.132.6.1 导向装置的选择.132.6.2 导向装置尺寸确定.132.7 模具其它主要零部件的设计.142.7.1 板料定位装置的设计.142.7.2 螺栓和销钉的选用.15第三章 工艺方案选择.173.1 冲压件的工艺确定.173.1.1 冲压件的工艺分析.173.1.2 零件材料的分析.193.1.3 确定工艺方案和模具形式.203.1.4 落料尺寸的计算.223.2 确定排样方案.223.2.1 确定排样、裁板方案.223.3 计算拉深次数.252.4 拉深冲压力的计算.263.4.1 落料过程.263.4.2、拉深过程.273.4.3 成型过程.283.5 冲压设备的选择.293.6 分析比较和确定工艺方案.30第四章 主要工艺参数的计算.364.1 确定各中间工序尺寸.364.2 计算各工序压力，选用压力机.37第五章 模具设计.425.1 模具结构形式选择.425.2 卸料弹簧的选择.425.3 模具工作部分尺寸和公差计算.435.4 模具其它零件的结构尺寸计算.445.5 工作原理.45第六章 冲压工艺过程卡的编写.47结 论.49致 谢.500第第 1 章章 前言前言 现在许多轿车门窗玻璃的升降(关闭和开启)已经抛弃了摇把式的手动升降方式，一般都改用按钮式的电动升降方式，即使用电动玻璃升降器来控制，也就是常说的“电动门窗” 。轿车用的电动玻璃升降器多是由电动机、减速器、导绳、导向板、玻璃安装托架等组成。因导绳的材料或制作工艺方式不同，又分为绳轮式、软轴式和塑料带式三种电动玻璃升降器。前二种是用钢丝绳做为导绳，后一种是用塑料带做为导绳。以普遍使用的绳轮式电动玻璃升降器为例，它是由电动机、减速器、钢丝绳、导向板和玻璃安装托架等零部件组成，安装时门窗玻璃固定在玻璃安装托架上，玻璃导向槽与钢丝绳导向板平行。 开启电动机，由电动机带动减速器输出动力，拉动钢丝绳移动玻璃安装托架，迫使门窗玻璃作上升或下降的直线运动。而塑料带式电动玻璃升降器的导绳采用塑料带，带上有孔，用来移动和定位塑料带，控制门窗玻璃的升降。 电动玻璃升降器结构的关键是电动机和减速器，这两者是组装成一体的，其中电动机采用可逆性永磁直流电动机，电动机内有两组绕向不同的磁场线圈，通过开关的控制可做正转和反转，也就是说可以控制门窗玻璃的上升或下降。 电动机是由双联开关按钮控制，设有升、降、关等三个工作状态，不操纵时开关自动停在“关”的位置上。操纵电路设有总开关（中央控制）和分开关，两者线路并联。总开关由驾车者，控制全部门窗玻璃的开闭，而各车门内把手上的分开关由乘员分别控制各个门窗玻璃的开闭，操作十分便利。 电动机的质量直接关系到电动玻璃升降器的正常工作，它一定要具有体积小、重量轻、防护等级高、噪声低、电磁干扰小、运行可靠等特点。现代轿车已广泛应用微电子技术，电机工作会发射电磁波干扰其它电器件的工作；前几年通用汽车公司一篇售后分析报告显示，近 40%的电动玻璃升降器故障是由电动机密封性差引起的。因此，减少电磁干扰和解决电机密封性问题巳成为近年汽车电机技术的热门话题。 90 年代中期以来，电动玻璃升降器的控制机构技术发展很快，电子模块控制形式大量应用于批量装车，并设有安全保护装置。例如博世公司生产的电动玻璃升降器系统，在电动机中埋植磁环，感应电机转速，在电子模块中埋植霍尔元件，感应电流，并通过电子模块控制对电动机的过流、过压及过热保护，而且当玻璃上升途中遇到人力障碍时会自动识别而反向运行，防止乘员夹伤。1第第 2 章章 冲裁工艺设计冲裁工艺设计2.1 冲裁工艺计算冲裁工艺计算2.1.1 工艺力和功的计算工艺力和功的计算冲裁力是指冲裁过程中的最大抗力，它是合理地选用冲压设备吨位和校检模具强度的重要依据。影响冲裁力的因素很多，主要有材料的机械性能、厚度、冲裁件周边长度、模具间隙以及刃口锋利程度等。Journal of Materials Processing Technology 139 (2003) 422427New processes to prevent a flow defect in the combinedforwardbackward cold extrusion of a piston-pinD.J. Leea, D.J. Kimb, B.M. Kimc,aDepartment of Precision Mechanical Engineering, Graduate School, Pusan National University, Pusan, South KoreabDepartment of Mechanical Design Engineering, Graduate School, Pusan National University, Pusan, South KoreacDepartment of Mechanical Engineering, Engineering Research Center for Net Shape and Die Manufacturing, Pusan National University, No. 3,Janjeon-Dong, Kumjeong-Ku, Pusan 609-735, South KoreaAbstractA flow defect of a piston-pin for automobile parts are investigated in this study. In the combined cold extrusion of a piston-pin, a lappingdefect,whichisakindofflowdefect,appearsbythedeadmetalzone.Thisdefectisevidentinproductswithasmallthicknesstobepiercedand is detrimental to dimensional accuracy and decrease of material loss. The flow defect that occurs in the piston-pin has bad effects onthe strength and the fatigue life of the piston-pin. Therefore, it is important to predict and prevent the defect in the early stage of processdesign. The best method that can prevent the flow defect is removing or reducing dead metal zone through the control of material flow.Finite element simulations are applied to analyze the flow defect. This study proposes new processes which can prevent the flow defect byremoving the dead metal zone. Then the results are compared with the results of experiments for verification. These FE simulation resultsare in good agreement with the experimental results. 2003 Elsevier Science B.V. All rights reserved.Keywords: Flow defect; Piston-pin; Material flow control; Forwardbackward extrusion; Dead metal zone; FE simulation1. IntroductionCold forming is extremely important and economical pro-cesses, especially for producing parts in large quantities.Because of advantages of cold forming such as high pro-duction rates, excellent dimensional tolerances and surfacefinish, mechanical and metallurgical properties, cold form-ing is by far the largest application of industry for producingparts.However, cold forged parts are also used in manufactur-ing aircraft, motorcycles, nuts and bolts 1, but it is possiblefor defects to occur in forged parts, depending on the de-formation history, forming conditions and material flow pat-tern, etc. The kind of defects are ductile fracture caused bythe state of stress and the deformation history, flow defectscaused by unstable material flow, and poor dimensional tol-erances caused by inferiority of the die and friction condi-tion. Further, defects in forged parts are classified as internaldefects and external defects 24.These defects have harmful effects on the quality of theproduct and an increase in the cost of production. Therefore,Corresponding author. Tel.: +82-51-510-3074; fax: +82-51-514-7640.E-mail address: bmkimpusan.ac.kr (B.M. Kim).it is important to predict and prevent defects in the earlystage of process design.Wifiet al. 5 studied ductile fracture in bulk formedparts, using different workability criteria by the finite ele-ment method. Kim and Kim 6 studied internal and exter-nal defects of cold extruded products with double ribs andperformed process design to prevent these defects.In this study is examined a defect which occurs in produc-ing a forwardbackward extrusion product, a piston-pin foran automobile part, and new processes are designed to pre-vent the defect by finite element method in the early stageof process design. Then the results are compared with theresults of experiments for verification.2. Forming and defect-occurrence analysis2.1. Forming processThe piston-pin is an automobile components used in thetransmission of power between the connecting rod and thecrankshaft. In the cold extrusion of a piston-pin, the designrequirements are to keep the same height of the forwardextruded part and the backward part (Fig. 1) without anydefect in the forged product, for use under high and repeated0924-0136/03/$ see front matter 2003 Elsevier Science B.V. All rights reserved.doi:10.1016/S0924-0136(03)00515-6D.J. Lee et al./Journal of Materials Processing Technology 139 (2003) 422427423Fig. 1. Shape and dimension of the piston-pin.Fig. 2. Photograph of a flow defect of a piston-pin.load. The material used for the piston-pin is AISI-4135H(Fig. 2) alloy steel, with the following flow stress behavior: = 768.06 0.139(MPa)Fig. 4. Distribution of effective strain and fracture value.Fig. 3. Conventional forming process for a piston-pin.The lubricant used is phosphate coating and bond lube. Thefriction factor, m, is assumed to be 0.1, which is confirmedby the ring compression test.The sequence of the conventional process for thepiston-pin is performed using a multi-stage former (Fig. 3).The first and second stages are pre-upsetting to eliminatedefects by the cropping process such as ovality and ec-centricity of the billet for improvement of dimensionaltolerances and die life whilst the third and forth stages areforward or backward extrusion for the forming of one di-rection from the web, and final stage is the piercing processfor the pin shape.However, the results of experiment for the conventionalprocessdisplayedadefectinthewebpartformedearlyinthethird process (Fig. 3). Especially, a nonuniform flow patternis observed in part of the defect occurrence, which lookslike a flow defect similar to lapping with an undesirable flowpattern.2.2. Prediction of defects by FE analysisDEFORM is used, which is commercial code of arigid-plastic FE program for forming and defect analy-sis. The diameter of the initial billet is 30mm and theheight is 61mm, the whole volume of final product being424D.J. Lee et al./Journal of Materials Processing Technology 139 (2003) 422427Fig. 5. Metal flow and velocity distribution, where a defect occurs according to stroke.43,118mm3. The forming is simulated with a conventionalprocess sequence.The maximum fracture value that can estimate the occur-rence of a crack 7 is small at 0.08 and is distributed ina position within the head part of the punch, so that a de-fect does not occur. Thus this defect is not one due to duc-tile fracture (Fig. 4). Then flow line-tracking scheme thatwas proposed by Altan and Knoerr 8 is performed for de-fect analysis. According to the progress of the punch stroke,severe variation of flow lines appears and discontinuity ofvelocity occurs in the part that a defect occurred in the ex-periment (Fig. 5).Consequently, the metal flows only in the backward di-rection without flow to the forward direction in the fourthprocess and metal near the web part is pulled up in the ribpart like a lapping defect. Therefore, the cause of the ini-tiation and development of the flow defect that occurred inpiston-pin is the velocity discontinuity between backwardand forward direction by the formation of a dead metalzone. This appearance evidently occurs in products like apiston-pin with a low thickness to be pierced for the dimen-sional accuracy and the decrease of material loss. A flowdefect occurring in a piston-pin has harmful effects on thestrength and the fatigue life of a piston-pin that has high andrepeated load at high temperature. Therefore, it is necessaryfor a new process to prevent the flow defect.3. Process redesign and analysis for the preventionof defectThe cause of the initiation and development of the flowdefect is the restriction of metal flow by the dead metalzone. For the elimination of the dead metal zone in theearly extruded part (3rd process) in the conventional process,the forward or backward extrusion process is modified tocombined forwardbackward extrusion, which is performedsimultaneously in the two directions. Because of the varietyof extrusion ratios and lengths in the forward and backwarddirections, the simultaneous completion of the material flowin the both directions is very difficult. Consequently, one ofthe directions is completed early, then material flow stoppedand dead metal zone appears in this part just like that in theconventional process.Therefore, in the case of piston-pin forming, the extrusionratio and the length of both directions are the same at 1.89and51mm.First,analysisofopendieforwardbackwardex-trusion is performed for an investigation of extrusion lengthsof the piston-pin. The difference of two extruded ribs is24.9mm and the backward extruded rib is shorter than theforward extruded rib as shown in Fig. 6.The metal flow of backward direction must be restrictedcompulsorily for the satisfaction of the design conditionsand this means the occurrence of a dead metal zone. There-fore, for the same extrusion length in both directions, threeFig. 6. Extrusion length in forwardbackward extrusion.D.J. Lee et al./Journal of Materials Processing Technology 139 (2003) 422427425Fig. 7. Modified process sequence for a multi-stage former.methods are proposed to control the metal flow without thecompulsory restriction of metal flow3.1. Change of preform shapeTo secure the same length of both directions from thecenter of web, it is required that the backward extrudedrib is performed by preform design as the difference ofboth-direction lengths at 24.9mm from the above results,before forwardbackward extrusion. Fig. 7 shows the mod-ified process sequence, and Fig. 8 shows the metal flow ofthe final stage of forwardbackward extrusion in this case.From the results of simulation, the lengths of two extrudedribs are 51mm, which is the dimension of the piston-pin andsatisfied the design condition. In addition, the metal flow isuniform in the defect zone where the flow defect occurredin the conventional process, and there is not a discontinu-ity of velocity in both extrusion directions. This means thatmetal flows uniformly in the whole process without a deadmetal zone by restriction of metal flow.Fig. 8. Metal flow of web in case of using preform.Fig. 9. Schematic diagram of the axially moving container die structure.3.2. Driving of extrusion containerThe driving extrusion container method 9 is used formetal flow control for the satisfying of the design condi-tion. This structure is that the extrusion container is movedin the counter direction to the early extruded one (Fig. 9).This has the effect of increasing the metal flow in the lateextruded direction and restricting metal flow in the early ex-truded direction. In the case of the piston-pin, because ofthe early completion of backward extrusion, the extrusioncontainer is moved in the forward direction for the increaseof metal flow to this direction. In this process, the princi-pal process variables are the relative velocity ratio of thepunch and the moving extrusion container, and the frictioncondition between the material and the moving extrusioncontainer.In this study, because the friction factor, m, is 0.1 be-tween the material and container, simulation is performedonly according to the variation of the relative velocity ratio(VC/VP= 0.1, 0.25, 0.5, 0.75, 1.0). If the relative velocityratio is smaller than the optimum which can complete form-ing simultaneously, extrusion in the backward direction iscompleted earlier than in the forward direction and a flowdefect occur in the same part as in the conventional process.Otherwise, if the relative velocity ratio is larger than the op-timum one, extrusion in the forward direction is completeearlier than backward direction and a flow defect occurs inthe opposite part to where a defect occurs in the conven-tional process.Therefore, for satisfaction of the design conditions, theoptimum relative velocity ratio is searched for by an opti-mization technique, the bisection method. From the result,the optimum relative velocity ratio is 0.48. Figs. 10 and 11show the deformation modality and metal flow according tothe relative velocity ratio (0.1, 0.48, 1.0) for a punch strokeof 42.7mm, respectively. Fig. 11(c) shows the metal flow426D.J. Lee et al./Journal of Materials Processing Technology 139 (2003) 422427Fig. 10. Deformation modality of the piston-pin according to the relative velocity ratio.Fig. 11. Comparisons of metal flow according to the relative velocity ratio.at the optimum relative velocity (0.48) where an improvedflow pattern without a flow defect can be noted.3.3. Modification of die structureA modification of the die structure is proposed whichcan restrict the metal flow of backward direction, which isdeformed early, for simultaneous completion of extrusion inboth directions. In this case, for simultaneous completionand the same length in both directions, the stripper, which isFig. 12. Schematic diagram of die structure using stripper.equipmentforpunchextractionfromproducts,isredesigned.If a fixed stripper of conventional type is used, a dead metalzone appears from the middle stage of backwardforwardextrusion by the restriction of material flow.Therefore, a structure is used that can delay the metal flowin the backward direction by spring force. Fig. 12 showsthe die structure. For this method, it is very important todecide the proper spring force for simultaneous completionof forming. Therefore, the necessary spring force for this iscalculated by FE simulation. From the simulation result, itwas 5t to be applied load to stripper. Fig. 13 shows metalflow in this case. The metal flow is similarly uniform at thedefect zone without discontinuity of velocity in comparisonwith other modification methods.Fig. 13. Metal flow of web in case of using stripper.D.J. Lee et al./Journal of Materials Processing Technology 139 (2003) 422427427Table 1Comparison process for each of the proposed methodConventional methodUse of preformUse of stripperUse of moving containerMaximum load (t)97.296.396.184.0Process of extrusion2 stage2 stage1 stage1 stageDefectExistNoneNoneNone4. Results and experimentFrom the FE simulation, the three proposed methodsare proper to prevent a flow defect by metal flow control.The characteristics of each process are as follows. The firstmethod that uses a preform needs three stage processes (pre-forming, forwardbackward extrusion, piercing) and has asimple die structure; however, the second method that usesa stripper and the third method that uses an axially mov-ing container need two-stage processes (forwardbackwardextrusion, piercing) and have a complex die structure. Inrespect of the forming load, the processes are similar toeach other.Especially,themaximumformingloadissmallerthanthatof other processes by about 10t in the case of the axiallymoving container, because the axially moving container in-creases material flow in the direction punch movement. It iscompared with the proposed method for forming by a pressin Table 1. In this study, an experiment using a preform isperformed and uses a multi-stage former having 250t ca-pacity for the verification of simulation. Etching for obser-vation of metal flow is performed to examine for a flowdefect for the piston-pin before piercing. Fig. 14 showsthe experiment result, based on the first proposed method,changing the preform. The experiment result shows thatmetal flow is uniform in the defect zone where the flow de-fect had occurred, and satisfied the simultaneous completionof forming and the same length in both extrusion directions.This tendency is in good agreement with the simulationresult.Fig. 14
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