曲轴铣端面打中心孔机床总体设计及夹具设计
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毕业设计
开题论证报告
专 业 机械设计制造及其自动化
学生姓名 钱 俊
班 级 B机制077
学 号 0710101715
指导教师 袁 健
完成日期 2011年3月19日
课题名称:曲轴铣端面打中心孔机床总体设计及其夹具设计
一、课题来源、课题研究的主要内容及国内外现状综述
1.课题来源:盐城市高精装备机电有限公司
2.主要内容:根据零件加工要求,设计一台曲轴铣端面打中心孔机床,具体进行曲轴铣端面打中心孔机床总体设计及夹具设计:
(1) 本机床设计成卧式结构形式,按图纸要求加工曲轴端面、中心孔;
(2) 根据被加工零件技术要求进行机床总体设计及夹具设计;
(3) 进行三图一卡设计,绘制机床总体设计图,夹具装配图及部分零件图,在设计计算说明书中要对零件的加工工艺进行分析、机床设计技术分析,进行定位方案和夹紧方案的设计,计算定位误差等,并写出相关的设计说明书。
3.国内外现状综述:
曲轴是引擎的主要旋转机件,装上连杆后,可承接连杆的上下(往复)运动变成循环(旋转)运动。是发动机上的一个重要的机件,其材料是由碳素结构钢或球墨铸铁制成的,有两个重要部位:主轴颈,连杆颈,(还有其他)。主轴颈被安装在缸体上,连杆颈与连杆大头孔连接,连杆小头孔与汽缸活塞连接,是一个典型的曲柄滑块机构。曲轴的润滑主要是指与摇臂间轴瓦的润滑和两头固定点的润滑. 曲轴的旋转是发动机的动力源。也是整个机械系统的源动力。
目前国内曲轴生产线多数由普通机床和专用机床组成,生产效率和自动化程度相对较低。粗加工设备多采用多刀车床车削曲轴主轴颈及拐颈,工序的质量稳定性差,容易产生较大的内应力,难以达到合理的加工余量。一般精加工采用MQ8260等曲轴磨床粗磨-半精磨-精磨-抛光,通常靠手工操作,加工质量不稳定。
随着贸易全球化的到来,各厂家已意识到了形势的严峻性,纷纷进行技术改造,全力提升企业的竞争力,近年来引进了许多先进设备和技术,进展速度很快。就目前状况来讲,这些设备和技术基本依赖进口。
曲轴粗加工将广泛采用数控车床、数控内铣床、数控车拉床等先进设备对主轴颈、连杆轴颈进行数控车削、内铣削、车-拉削加工,以有效减少曲轴加工的变形量。曲轴精加工将广泛采用CNC控制的曲轴磨床对其轴颈进行精磨加工。此种磨床将配备砂轮自动动平衡装置、中心架自动跟踪装置、自动测量、自动补偿装置、砂轮自动修整、恒线速度等功能要求,以保证磨削质量的稳定。高精设备依赖进口的现状,估计短期内不会改变。
二、本课题拟解决的问题
组合机床总体设计问题,例如结构选型、总体布局;
组合机床设计的精度要求,例如孔的形状精度,位置精度;
组合机床传动方案的确定;
标准件、通用件的选择;
详细设计相关问题,例如相关强度校核、刚度校核、局部结构设计问题的方案确定;
三、解决方案及预期效果
解决方案:
1. 制定工艺方案
在确定工艺方案制定合理之前,通过毕业设计实习深入现场了解被加工零件的结构特点、加工部位、尺寸精度、表面粗糙度和技术要求,定位、夹紧方式等,工艺方法和加工过程采用的刀具、辅具,切削用量情况及生产率要求,以求理论联系实际,从而确定零件在组合机床上完成的工艺内容和方法,决定刀具种类、结构型式数量及切削用量。
2. 确定机床配置型式及结构方案
根据选定的工艺方案,确定了本课题的配置型式:卧式组合机床,并采用工序集中进行加工。定出影响机床总体布局和技术性能的主要部件的结构型式。
3. 总体设计
在选定了工艺方案并确定了机床配置型式、结构方案的基础上,进行三图一卡的设计、绘制。一般,在总体设计的过程中,需要对机床夹具方案进行考虑,画出夹具方案草图。
4. 部件设计
根据确定的工艺和结构方案,按照加工示意图和机床联系尺寸图等开始设计,绘制夹具总装图,在绘制好的夹具总装图的基础上,绘制所有的非标准零件图。
预期效果:
1.机床应能满足加工要求,保证加工精度;
2.机床应运转平稳,工作可靠,结构简单,装卸方便,便于维修、调整;
3.机床尽量能用通用件(中间底座可自行设计)以便降低制造成本;
4.机床各动力部件用电气控制;
5. 组合机床结构合理,符合工作现场的需要,更易于操作和使用;
6. 组合机床拆卸方便、更易于维护;
四、课题进度安排
2月21日~3月19日.毕业设计前期阶段。
毕业实习,查阅资料,市场调查,到多个公司实践,撰写实习报告。
论文总体构思方案,填写开题报告。
3月20日~5月7日. 设计初稿阶段。
完成总体设计图、部件图、零件图。
5月8日~5月25日. 中期工作阶段。
完善设计图纸,编写毕业设计说明书,中期检查。
5月26日~5月27日.毕业设计预答辩。
5月28日~6月6日.毕业设计整改。
图纸修改、设计说明书修改、定稿,材料复查。
6月7日~6月8日.毕业设计材料评阅。
6月9日~6月10日.毕业答辩。
6月11日~6月15日.材料整理装袋。
五、指导教师意见
签名
年 月 日
六、专业系意见
签名
年 月 日
七、学院意见
签名
年 月 日
3
表2-4 生产率计算卡
被
加工
零件
图号
4
毛坯种类
铸件
名称
曲轴
毛坯重量
材料
HT150
硬度
240~290HB
工序名称
铣端面打中心孔
工序号
序号
工步
名称
被加工零件数量
加工直径(mm)
加工长度
(mm)
工作行程
(mm)
切削速度
(m
/min)
每分钟转速
(r/
min)
进给量
(mm/r)
进给速度
(mm
/min)
工时(min)
机加工
时间
辅助
时间
共计
1
装卸工件
1
1.5
1.5
2
快进(铣端面)
20
0.004
0.004
3
工进(铣端面)
50
5
5
62.8
250
2.4
600
0.008
0.008
4
快退(铣端面)
25
0.005
0.005
5
中间滑台快进
450
0.09
0.09
6
快进(打中心孔)
20
0.004
0.004
7
工进(打中心孔)
15.5
15.5
6.28
125
25
0.62
0.62
8
快退(打中心孔)
35.5
0.007
0.007
9
死挡铁停
0.06
0.06
备 注
装卸工件时间取决于操作者熟练程度,本机床计算时取1.5min
总计
2.298min
单件工时
2.298min
机床生产率
6.38件/h
机床负荷率
24.4%
Jun.2007 Journal of China University of Mining&Technology Vol.17 No.2 J China Univ Mining&Technol 2007,17(2):02720276 Series Design of Large-Scale NC Machine Tool TANG Zhi Engineering and Mechanical Institute,Donghua University,Shanghai 201620,China Abstract:Product system design is a mature concept in western developed countries.It has been applied in war industry during the last century.However,up until now,functional combination is still the main method for product system de-sign in China.Therefore,in terms of a concept of product generation and product interaction we are in a weak position compared with the requirements of global markets.Today,the idea of serial product design has attracted much attention in the design field and the definition of product generation as well as its parameters has already become the standard in serial product designs.Although the design of a large-scale NC machine tool is complicated,it can be further optimized by the precise exercise of object design by placing the concept of platform establishment firmly into serial product de-sign.The essence of a serial product design has been demonstrated by the design process of a large-scale NC machine tool.Key words:large-scale NC machine tool;series product design;optimized design CLC number:TH 12 1 Introduction Large-scale machine tool designs are management programs requiring participation of different disci-plines including engineering,behavioral studies,color research,ergonomics and corporate identity1.At present,functional designs are emphasized in China,while in western countries the multi-color identity system and series product definitions have entered the field of industrial design.It is quite com-mon in China to imitate products from Taiwan and other similar territories,resulting in the phenomenon where many products in the market are of the same quality.There are almost no differences among large-scale numerical controlled(NC)machine tools made by different factories.It is vital to introduce series product designs into the Chinese production processes.Back in the 1930s,the designers in GM adopted a new design mode,i.e.planned obsolescence2.Ac-cording to this plan,the style of cars at least should have small changes every two years and dramatic changes every 34 years,which provide regularly a new style of cars.The aim of the plan was to con-vince customers to give up their old cars and to pur-sue the new style.Theoretically,planned obsoles-cence established serial product designs,elevated planned product design to the level of management decisions inside the company and increased sales be-cause of the introduction of serial product designs.From the 1930s to the 1960s,system designs did not improve much due to the financial crisis and the Second World War.However,the requirement of the war had stimulated mass production of consumer products,after generating a large number of cheap industrial products,a spinoff from the war.After the Second World War,system designs and serial product designs developed by GM and a number of other car manufacturers emerged in Italy,the UK and Germany.This was especially true for the ULM Design Institute whose system of industrial designs became the stan-dard for scientific application of industrial designs.This developed to an advanced level and much atten-tion was directed to cooperation among firms.It is clear that the effect of such changes on,for example,BRAUN,was very significant3.From 1960 to 1970,Japan started product development on a multi-na-tional company level,while at the same time the Japanese government established industrial product export norms.During the last 20 years,a number of institutions and organizations have been engaged in research of design processes,design methods,and design management4.At present,in terms of the serial design of a Received 12 October 2006 accepted 15 November2006 Corresponding author.Tel:+86-13761641467;E-mail address: TANG Zhi Series Design of Large-Scale NC Machine Tool 273large-scale NC machine tool,it is important to main-tain the inner characteristics of the firm,which is the core of the serial design system.Fig.1 is the proto-type of a large-scale NC machine tool from a particu-lar company in China.Fig.1 Original prototype of machine tool The style of the original prototype of the machine tool in Fig.1 is actually consistent with design sys-tems of the middle of the 20th century.It has some problems:1)bare engine;2)sharp angle style of the corner;3)accessories do not match the main machine;4)line arrangement is not orderly;5)open style of the door is out of date;6)single color,lack of the inden-tification and 7)entire style is dated,falls short of advanced product identity system.Therefore this style is too direct in expressing the function and form of the product.It is important therefore,that its essen-tial functional features are consistent with the design of a serial product.2 Product Identity System Generally,the product identity factor determines the behavior of a particular company,which is the very essence of the product identity system,i.e.,to identify clearly with a particular product.Therefore,the identity system should 1)be able to attract maxi-mum social attention,2)agree with the visual con-ceptual standards of the company,3)be provided with a characteristic logo,4)be able to impress others,5)meet the needs of different types of products,6)conform to aesthetic taste and 7)does not signifi-cantly increase production costs caused by the devel-opment of the new design.From the point of view of product identity,these are the requirements in order to raise the price of the product and meet market competition.Similar to the“sense and simplicity”of the Philips label,the em-bodiment of its core value is the key for a company to obtain the enthusiastic acceptance from the public.Its platform establishment,optimized design and modu-lar management should be introduced as the main factor of serial products to support the product iden-tity system at the company level5.Fig.2 is the diagram of design platform.Before establishing the identity system,a common platform for a large-scale serial NC machine tool needs to be provided and then optimized in order to determine which platform suits the design of a par-ticular product.Therefore,the platform is the key for the future serial product.Fig.2 Introduction of design platform 3 Establishing Platform for Product 3.1 Process of platform establishment For different structures of product integration,the platform is usually the most effective way to deter-mine the cost.The time for design can be reduced and productivity can be raised because of anamorphic products from the repeated platform.Especially,for a large-scale NC machine tool,it is important that the customized products for specific regions are easily and effectively adopted on the established product platform6.The purpose for establishing a platform is not for the product function but for concentrating on the de-sign of the serial product and on other systems relat-ing to product technology.In terms of the platform,the engineering team should build a model of the product system which involves the system framework for describing the product precisely and then report-ing to the designer as a reference for establishing the platform(Fig.3).3.2 Evaluation of the platform establishment Following are four basic evaluation criteria7:1)Material cost and production cost(which will influence the final price of the product).2)The cost of inventory.3)Visual requirement.4)Ergonomics.Enumeration of these criteria is the basis for serial product differentiation.Fig.4 shows a list of the se-rial products for four alternative projects.The prod-ucts are listed on the top of the chart and are pre-sented as columns.The serial products are divided into parts for analytical convenience.Four different series are presented at four different platforms in which series A involves a power supply,series B in-volves a power supply,an oil slot and wiring,series C involves a power supply,a base and a line controller and series D involves a power supply,an oil filter and Journal of China University of Mining&Technology Vol.17 No.2 274an electrical source.Their scores are recorded ac-cording to the following rule:1)the base design,“0”;2)better than base design,“+”;3)worse than base design,“”.Fig.3 Platform of design process for machine tool Sort of product Sort 1 Sort 2 Sort 3 Sort 4 Chose platform A B C C A B C C A B C C A B C C Materials cost 0 0 0 0 0 0 0 0 Development cost 0 0 Requirement of vision 0 0 0 0 0 0 0 0 Evaluation criteria Ergonomics 0 0 0 0 Summary 0 1 2 2 22222222 1 1 0 0 Fig.4 Selection chart of product platform and serial products After the evaluation,we obtain an aggregate score,which is the basic optimized platform project.For a project such as the large-scale NC machine tool,however,it is vital to build a partly optimized design for product parts.4 Optimized Design of Product The optimized product design is usually not aimed at the platform but at a particular product and in the structural design,it should follow the function,such as the improvement of the door style of our machine tool.The platform and single optimized product de-signs are usually adopted in large-scale equipment.By taking advantage of the basic platform,new,ab-normal products can be easily be developed.Modular development,armature plate techniques and quickly formed skills come quite easily and are sufficient to meet the needs of the market.However,there are some disadvantages to a basic platform.Generally speaking,in a series only one product is compara-tively successful in material and development costs,visual requirements and human factors.This is the so-called flagship product with respect to other lower level serial products.Assume product i was a singular design,not based on a platform,so it can be expressed as an optimiza-tion problem.Now let us try to optimize an obj ctive function in terms of the structural variableiefx?,re-stricted by the function g,cost and other constraints8,then we have()minpixfx?restriction function ,()0ig x?budget restriction ()iiicostxB?,where g stands for a restriction function,cost for se-rial products and B for budget.The planned work based on the platform can construct an optimized model.Before selecting the product platform,we must first determine what are the common parts and what can be isolated as an anamorphous part.When the cost of every anamorphous part is decreased to its lowest level,the cost of the whole series is also re-duced to the lowest level.So,the optimization should be operated at two layers,namely the platform and anamorphous part.The product function based on the platform is decided by the variable,the part shared with the same platform could be described by the variable set.As well,the formula can also be used in the design of a single product i.On the platform and for the variable concerned,different optimization TANG Zhi Series Design of Large-Scale NC Machine Tool 275processes can be made flexible.The optimized issue is described by minpx?()min,iyipyxif xx?Function limit (),0iipygxx?,Budget limit (),iipyicostxxB?,where Bis the budget of the serial product.This mathematical expression is a simple descrip-tion for the optimization process.Actually we still adopt a small scale modular design for the details.For these large-scale NC machine tools,the modular de-sign is very good for it can deal with the details of the inner parts of the product,resulting in a low cost of R&D and inventory.Moreover,the optimized design can be applied in the function modular combination,just like the big difference would appear on different sized machine tools in the structure and quantity of the doors.However,the optimized design needs some adjustment for the installment of the console and wiring set to fit the size and the application.5 Module Design of Product Standardization of accessories and a quick forming of the shape are the two main advantages of the modular design.Based on these two characteristics,a modular product generally can be divided into several layers in one system9.However,because of the un-derstanding from the different angles,the standard and the result of the module are not unique;the final relationships of sub-functions are probably a holistic or modular construction.There are two product modules:one based on a functional module and the other based on a produc-tion module.The first one is set from the general product function and is expressed by its sub-function.For the second,the production takes into considera-tion the combination of some accessories in the manufacturing process,forming the assembled mod-ule(Fig.5).The module mentioned here is at a con-ceptual level;its function has the characteristics of production and assembly.Fig.5 Design module of product system structure 6 Parameter Set of Serial Product 6.1 Size parameter In terms of complicated products like our large-scale NC machine tool,the determination of parame-ters is quite important.Its functionalism is always the first thing to be considered when we regulate the rela-tive size.These days,undoubtedly,the products that are subjected to global competition,increasingly are ergonomic designs of classical products and become the preferred products on a worldwide level.In the design of a flagship product,one from a se-rial product,the redundant,complicated and de-humanizing details have been eliminated from the design according to certain standards.In the design process,the aesthetic,structure and interaction must be taken into consideration.Clearly,the base of the machine tool and the power supply can be a 3D iden-tity standard(Fig.6),i.e.,the symbolized design of the new product.So the size and proportional pa-rameters are regulated.For different kinds of propor-tional parameters,seen in Fig.7,the proportion of the doors,moveable doors and power supply have been presented.All of the parameters are determined based on ergonomics,especially given the body scale of Asiatic people 10.Fig.6 New machine tool concepts 6.2 Parameter set up by the chart As Fig.4 shows,there are four sorts of products,each has four platforms named A,B,C and D.Engi-neers are asked to choose which platform is appropri-ate for each sort of product.They are also asked to rate the remaining four factors:material cost,devel-opment cost,visual requirement and ergonomics,corresponding to each sort of product11.Journal of China University of Mining&Technology Vol.17 No.2 276 Fig.7 Engineering chart design standard 7 Conclusion The inevitable result from a serial product design is a real product.It is necessary to adjust the parameter set in the process of final assembly.Any single product which can occupy the target market will become well known in the near future and the development direction of a serial product de-sign must receive a well earned reputation around the world.Every improvement in product design does not mean a thorough change.A well planned design di-rection at the beginning is the key in project man-agement.Under the guidance of market economics,it is necessary to fulfill the expectations of the serial product design,for if we cannot use the new product development and design processes efficiently,we will loose the resources used in the design of the serial product.References 1 Olins W.The Wolf Olins Guide to Corporate Identity.London:The Design Council,1990.2 Wang S Z.The World Modern Design History.Beijing:China Youth Press,2002.3 Olins W.Corporate Identity-Making Business Strategy Visible through Design.London:Thames&Hudson,1994.4 Oakley M.Design Management:A Handbook of Issues and Methods.Oxford:Basil Blackwell,1990.5 Otto K N.Product Design.Beijing:Publishing House of Electronics Industry,2002.6 Webb A.The Project Management of Successful Products.Shanghai:Shanghai University of Financial and Economic Press,2004.7 Schein E.Coming to a new awareness of organizational culture.Sloan Management Review,1984,25(124):3341.8 Project Management Association.The Guide of Project Management Knowledge System.Beijing:Publishing House of Elec-tronics Industry,2005.9 Trott P.Innovation Management&New Product Development.London:Pearson Education,2002.10 Gillian H,Bill H.Total Design-Managing the Design Process in the Service Sector.Bath:Pitman Publishing,1993.11 Roy D R.Design and the Economy(2nd Edition).London:The Design Council,1990.
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