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机械专业毕业设计外文翻译--工艺规程制订

机械专业毕业设计外文翻译--工艺规程制订
机械专业毕业设计外文翻译--工艺规程制订

附录

Process Planning

The product design is the plan for the product and its components and subassemblies.To convert the product design into a physical entity ,a manufacturing plan is needed .The activity of developing such a plan is called process planning .It is the link between product design and manufacturing .Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product .In the present chapter ,we examine processing planning and several related topics.

At the outset ,we should distinguish between process planning and production planning ,which is covered in the following chapter. Process planning is concerned with the engineering and technological issues of how to make the products and its parts. What types of equipment and tooling are required to fabricate the parts and assemble the product ? Production planning is concerned with the logistics of making the product .After process planning is concerned with ordering the materials and obtaining the resources required to make the product in sufficient quantities to satisfy demand for it.

Process Planning

Process planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation.The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant .Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design.This is a

point we will return to later.

Process planning is usually accomplished by manufacturing engineers .(Other titles include in industrial engineer.) The process planner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings .Based on the planner’s knowledge,skill,and experience ,the processing steps are developed in the most logical sequence to make each part .Following is a list of the many decisions and details usually include within the scope of process planning :

.Interpretation of design drawings.The part of product design must be analyzed (materials,dimensions,tolerances ,surface finished,etc.) at the start of the process planning procedure.

.Process and sequence.The process planner must select which processes are required and their sequence.A brief description of processing steps must be prepared.

.Equipment selection . In general , process planners must develop plans that utilize existing equipment in the plant .Otherwise ,the component must be purchased ,or an investment must be made in new equipment .

.Tools ,dies,molds,fixtures,and gages.The process must decide what tooling is required for each processing step.The actual design and fabrication of these tools is usually delegated to a tool design department and tool room ,or an outside vendor specializing in that type of tool is contacted.

Methods analysis .Workplace layout ,small tools ,hoists for lifting heavy parts ,even in some cases hand and body motions must be specified for manual operations .The industrial engineering department is usually responsible for this area.

.Work standards.Work measurement techniques are used to set time standards for each operation .

.Cutting tools and cutting conditions.These must be specified for machining

operations ,often with reference to standard handbook recommendations.

Process Planning for parts

For individual parts,the processing sequence is documented on a form called a route sheet .(Not all companies use the name route sheet ;another name is “operation sheet .”)Just as engineering drawings are used to specify the product design ,route sheets are used to specify the process plan .They are counterparts,one for product design ,the other for manufacturing .A typical route sheet ,illustrated in Fig.21.1,includes the following information: (1) all operations to be performed on the work part ,listed in the order in which they should be performed ; (2) a brief description of each operation indicating the processing to be accomplished,with references to dimensions and tolerances on the part drawing; (3) the specific machines on which the work to be done; and (4) special tooling such as dies molds ,cutting tools,jigs or fixtures ,and gages.Some companies also include setup times ,cycle time standards,and other data.It is called a route sheet because the processing sequence defines the route that the part must follow in the factory .Some of the guidelines in preparing a route sheet are listed in Table 21-1.

Decisions on process to be used to fabricate a given part are based largely on the starting material for the part .This starting material is selected by the product designer.Once the material has been specified ,the range of the possible processing operation is reduced considerably .The product designer’s decisions on starting material are based primarily on functional requirements ,although economics and manufacturability a role in the selection.

A typical processing sequence to fabricate an individual part consists of : (1) a basic process,(2)secondary processes ,(3) operations to enhance physical properties,and (4)finishing operations.The sequence is shown in Fig.21.2. A basic process determines the starting geometry of the workpart.Metal casting ,plastic molding ,and roling of sheet metal are examples of basic processes.The starting geometry must often be refined by secondary

processes,operations that transform the starting geometry (or close to final geometry ).The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry.When sand casting is the basic processes,machining operations are generally the second processes .When a rolling mill produces sheet metal,stamping operations such as punching and bending are the secondary processes.When plastic injection molding is the basic process ,secondary operations are often unnecessary,because most of the geometric features that would otherwise require machining can be created by the molding operation.Plastic molding and other operation that require no subsequent secondary processing are called net shape processes.Operations that require some but not much secondary processing (usually machining ) are referred to as near net shape processes.Some impression die forgings are in this category .These parts can often be shaped in the forging operation(basic processes)so that minimal machining (secondary processing )is required .

Once the geometry has been established ,the next step for some parts is to improve their mechanical and physical properties .Operations to enhance properties do not alter the geometry of the part;instead,they alter physical properties .Heat treating operations on metal parts are the most common examples .Similar heating treatments are performed on glass to produce tempered glass.For most manufactured parts ,these property-enhancing operations are not required in the processing sequence ,as indicated by the alternative arrow path in Fig.21.2.

Finally finish operations usually provide a coat on the work parts (or assembly )surface. Examples inclued electroplating ,thin film deposition techniques ,and painting.The purpose of the coating is to enhance appearance ,change color ,or protect the surface from corrosion,abrasion ,and so forth .Finishing operations are not required on many parts ;for example, plastic molding rarely require finishing .When finishing is required ,it is usually

the final step in the processing sequence .Table 21-2 presents some typical processing sequences for common materials used in manufacturing .

In most cases,parts and materials arriving at the factory have complete their basic process.Thus ,the first operation in the process plan follows the basic process that has provided the starting geometry of the part ..For example ,machined parts begain as bar stock or castings or forgings,which are purchased from outide vendors.The process plan begains with the machining operations in the company’s own plant .Stempings begin as sheet metal coils or strips that are bought from the rolling mill.These raw materials are supplied outside sources so that the secondary processes,property-enhancing operations ,and finishing operatios can be performed in the company’s own factory.

In addition to the route sheet ,a more detailed description of eac operation is usually prepared. This is filed in the particular production department office where the operation is performed.It lists specific details of the operation ,such as cutting conditionsand toolings(if the operation is machining )and other instructions that may be useful to the amchine operator.The desciptions often include sketches of the machine setup.

Processing Planning for Assemblies

The type of assembly method used for a given product depends on factors such as : (1) the anticipated production quantities ;(2) complexity of the assembled product ,for example ,the number of distinct components ;and (3)assembly processes used ,for example ,mechanical assembly versus welding .For a product that is to be made in relatively small quantities ,assembly is usually performed on manual assembly lines .For simple products of a dozen or so components,to be made in large quantities ,automated assembly systems are appropriate .In any case ,there is a precedence order in which the work must be accomplished .The precedence requirements are sometimes portrayed graphically on a precedence diagram.

Process planning for assembly involves development of assembly instructions,but in more detail .For low production quantities,the entire assembly is completed at a single station .For high production on an assembly line ,process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing.The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution.As in process planning for individual components ,any tools and fixtures required to accomplish an assembly task must be determined ,designed,and built;and the workstation arrangement must be

laid out.

工艺规程制订

产品设计是用于产品,及它的部件装配的计划. 为了把产品设计转换成一个实际物

体 ,这需要一个制造计划。而制订一个这样的计划的行动就叫做工艺规程制订。它是产品设计和制造之间的连接.工艺规程制订包括决定加工顺序和制造产品所必须完成的装配步骤.在以下文章中,我们将解释工艺规程制订和他的一些相关主题。

文章开始, 我们应该区别在下列文章中被反复提到的工艺规程制订和生产计划。工艺规程制订与如何制造产品和它的零件等工程技术问题有关.制造零件和装配产品需要什么样的设备和工具? 工艺规程制订与产品制造物流管理有关系。它在工艺规程制订后面与原料分类及获得满足制造充分数量产品要求的资源有关.

工艺规程制订

工艺规程制订包括决定最适当的制造及装配步骤和顺序,在这些顺序和步骤中他们必须根据所提出的详细的设计说明书规范完成给定零件或产品制造. 能够被计划的工

艺范围和多样性通常由于公司车间可用设备和技术能力而受到限制.在公司内部不能够制造的零件必须到外部市场购买. 工艺规程制订所提及的工艺选择同样也受到详

细设计资料的限制.我们稍后将会回到这一点.

工艺规程制订通常是由制造工程师完成的.( 工业工程师拥有其他权利.) 工艺制

订者必须熟悉工厂中详细可用的制造流程并且能够说明工程图。基于制订者的知识,技术和经验, 用于制造每个零件的工艺步骤以最合乎逻辑的顺序被发展制订。下列各项是在工艺规程制订范围里的许多决定和详细资料:

.设计图的说明. 在工艺规程制订的开始,产品设计的这一部分( 材料,尺寸,公差 ,表面处理,等等)必须进行分析。

.工艺和顺序. 工艺制订者必须选择哪一个工艺是必需的及必需工艺的序列。此外还必须准备好一个简短的工艺步骤描述.

.设备选择. 大体上,工艺制订者必须逐步展开利用工厂现有机器的计划.另外,组

件必须被购买或在新设备上的投资必须被制定.

.工具,冲模,铸模,夹具,量具. 工艺必须决定每个工序需要什么工具.这些工具的实际设计和制造通常通过委派工具设计部门和工具库或者联系专攻那种工具制造的外面厂商来完成.

.方法分析. 车间规划,小工具,提升重物的提升间,甚至在一些人工操作情景中的肢体动作也被指定.

.操作步骤. 工作测量技术被用来为每个操作设定时间标准。

.切削工具和切削条件. 这些必须对加工操作通过推荐标准手册来进行详细说明. 零件工艺规程制订

对于单个零件,加工顺序通过一种被称为进路表的表格来进行文件证明备份. ( 不是所有的公司使用进路表这个名字;另外的一个名字是 " 操作说明书。”)就如工程图被用于详细说明设计产品一样,进路表被用于详细说明工艺计划. 他们是类似的, 一个用于产品设计 , 另一个用于制造。典型的进路表 ,如图.21.1 中举例,包括下列信息: (1)所有工作部分要执行的操作都按照他们应当被执行的顺序列出来;(2)一个指出关于零件图尺寸公差必须完成加工的每个操作的简短描述;(3)用于完成这个操作的特定设备;(4)象冲模,钻模,切削刀具,钻夹具或夹具,和量具这样的特定工具.一些公司还包括时间设置,周期标准和其他数据.他被称为进路表是因为工艺顺序规定了零件在工厂中必须遵循的路线.如表21-1中,列出了在准备一个进路表时所需要的一些指导方针.

制造单个零件的典型加工顺序包括: (1) 一个基本工序,(2) 二级工序,(3) 提高物质特性工序,和(3) 最后工序..一个基本工序决定了工件的起始造型.金属铸件,塑料成型,金属精炼是基本工序中的实例. 起始造型常常必须通过改变起始造型操作(或者接近于最终造型)的二级工序来精制. 二级工序习惯于和基本工序一起提供起始造型.当砂型铸造是基本工序,车加工通常是二级工序.当轧钢厂制造金属片是基本工序,冲压操作象冲裁和弯曲通常是二级工序.当塑料注入成型是基本工序时,二级工

序通常是不必要的,因为他的大多数几何特征制造通过别的方式如成型制造来完成.塑料成型和其他操作的二级工序被称为净成型工序的并发二级工序.需要一些但并不多的二级工序的操作就是所提到的近似净成型工序.许多有印象的摸锻件就是这一类.这类零件能够经常在锻造(初级工序)阶段被成型,因此减少了必要的加工(二级工序).

一旦模型被建立,许多零件的下一步是改良它们的机械物理性能.提高特性工序并不改变零件模型,然而,它却能改变零件的物理特性.金属零件的热处理操作就是最普通的实例.类似的如玻璃通过热处理来制造钢化玻璃.对于大多数零件的制造来说,这些特性加强工序在加工工序中并不需要.

最后工序通常对零件(或装配体)的表面提供一个涂层.例如电镀,薄膜沉积技术,涂漆.表面处理的目的是改善外观,改变颜色,或者表面保护防止腐蚀和磨损等等.在很多零件中最后工序是并不需要的;例如,塑料成型就很少需要最后程序.当必须需要最后程序,他通常是加工顺序的最后一步.

装配工艺规程制订

一个既定产品的典型装配方法由以下因素决定的: (1)预期产品数量;(2)装配产品的复杂性,例如,不同组件的数量;和(3)常用装配工艺,例如,机械定位焊接.对于小数量产品,通常在人工装配线上进行装配.对于大量制造的一打或这样组件的简单零件,要采用适当的自动化装配线.无论如何,这里有一个工作必须被完成的优先顺序.这个优先需求经常用一个优先表来进行图表描绘.

装配工艺规程制订包括装配指令的发展,但是更详细地,对于小批量生产, 在一个岗位完成整个装配。对于一个装配线上的大批量生产,工艺规程制订由一种分配工作条件到装配线个别工位并被叫做人工投入线性平衡法的程序组成.这种装配线按照装配线平衡解决方案决定的顺序发送工作单元到个别工位.在个别组成,任意工具或夹具的工艺规程制订时,一条装配线的决定,设计,和制造必须被完成,并且工作站的必须被列出来.

毕业设计外文翻译资料

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冲压模具技术外文翻译(含外文文献)

前言 在目前激烈的市场竞争中,产品投入市场的迟早往往是成败的关键。模具是高质量、高效率的产品生产工具,模具开发周期占整个产品开发周期的主要部分。因此客户对模具开发周期要求越来越短,不少客户把模具的交货期放在第一位置,然后才是质量和价格。因此,如何在保证质量、控制成本的前提下加工模具是值得认真考虑的问题。模具加工工艺是一项先进的制造工艺,已成为重要发展方向,在航空航天、汽车、机械等各行业得到越来越广泛的应用。模具加工技术,可以提高制造业的综合效益和竞争力。研究和建立模具工艺数据库,为生产企业提供迫切需要的高速切削加工数据,对推广高速切削加工技术具有非常重要的意义。本文的主要目标就是构建一个冲压模具工艺过程,将模具制造企业在实际生产中结合刀具、工件、机床与企业自身的实际情况积累得高速切削加工实例、工艺参数和经验等数据有选择地存储到高速切削数据库中,不但可以节省大量的人力、物力、财力,而且可以指导高速加工生产实践,达到提高加工效率,降低刀具费用,获得更高的经济效益。 1.冲压的概念、特点及应用 冲压是利用安装在冲压设备(主要是压力机)上的模具对材料施加压力,使其产生分离或塑性变形,从而获得所需零件(俗称冲压或冲压件)的一种压力加工方法。冲压通常是在常温下对材料进行冷变形加工,且主要采用板料来加工成所需零件,所以也叫冷冲压或板料冲压。冲压是材料压力加工或塑性加工的主要方法之一,隶属于材料成型工程术。 冲压所使用的模具称为冲压模具,简称冲模。冲模是将材料(金属或非金属)批量加工成所需冲件的专用工具。冲模在冲压中至关重要,没有符合要求的冲模,批量冲压生产就难以进行;没有先进的冲模,先进的冲压工艺就无法实现。冲压工艺与模具、冲压设备和冲压材料构成冲压加工的三要素,只有它们相互结合才能得出冲压件。 与机械加工及塑性加工的其它方法相比,冲压加工无论在技术方面还是经济方面都具有许多独特的优点,主要表现如下; (1) 冲压加工的生产效率高,且操作方便,易于实现机械化与自动化。这是

机械专业毕业论文外文翻译

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电气专业毕业设计外文翻译

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