【机械类文献翻译】机床夹具的分类与构成

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翻译题目::机床夹具的分类与构成翻译题目
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Machine classification and pose fixture
1fixture in the role of machining
Workpiece clamping fixture is a kind of process equipment,it is widely used in mechanical machining of the manufacturing process,heat treatment,assembly, welding and testing processes.In the use of metal-cutting machine tools collectively referred to as the jig fixture.n a modern production machine is an indispensable fixture of the process equipment,machining of the workpiece,the processing requirements in order to ensure.First of all to the workpiece and the machine tool relative to a correct position,and this location during processing does not change the impact of external forces.To this end,during the pre-machining,workpiece clamping must be good.There are two ways to clamp workpiece:one is directly clamping the workpiece in the machine table or on the chuck;The other is the workpiece in the fixture on the fixture.The first method used when the workpiece clamping,the general design requirements have to press lines in the surface to draw the size and location,clamping,or when the needle is zoned dial indicator to find is after the clamping.This method need special equipment,but low efficiency,are generally used for one-piece and small batch rge quantities,mostly with the workpiece clamping fixture.With the merits of the workpiece clamping fixtures are as follows: (l)Guarantee the stability of the machining accuracy of workpiece.Workpieces with clamping fixture,the workpiece relative to the location of tool and machine tool to ensure the accuracy of the fixture from the technical level of workers,so that a number of workpiece machining accuracy of the line.
(2)To improve labor productivity.Workpiece clamping fixture can facilitate the user easily、rapidly,and the workpiece does not need to find is crossed,can significantly reduce the supplementary working hours,to improve labor productivity; workpiece in the fixture after the fixture to improve the rigidity of the workpiece,thus cutting the amount of increase,to improve labor productivity;can use more pieces of multi-workpiece clamping fixture,and the use of efficient clamping bodies,to further improve labor productivity.
(3)To expand the use of machine tools.Machine tools in general use a dedicated machine tool fixture can expand the scope of the process and give full play to the potential of machine tools to achieve a multi-machine use.For example,the use of a dedicated fixture can be easily Lathe processing small box to the workpiece.Even in the lathe out of oil,a reduction of expensive dedicated machines,reducing the cost,
which is particularly important for small and medium-sized factories.
(4)To improve the operator's working conditions.As the pneumatic,hydraulic, electro-magnetic power source,such as the application in the fixture,on the one hand to reduce the labor intensity of workers;the other hand,it guarantees the reliability of the workpiece clamping,and to achieve the interlocking machine,to avoid accidents, ensure the operator safety and machine tool equipment
(5)To reduce costs.In mass production after the use of fixture,from stem to increase labor productivity,lower level technical workers,as well as lower scrap and other reasons,obviously to reduce the production costs.
Fixture manufacturing cost-sharing in a group of workpieces,each workpiece to increase the cost is very minimal,far less than as a result of increased labor productivity and reduce costs.The greater volume of workpiece,fixture made to use has become more significant economic benefits.
2Fixture Category
2.1General characteristics of the fixture by Category
According to the production in different types of fixtures in the common characteristics of machine tool fixture fixture can be divided into general,special fixtures,adjustable clamp,and automatic line of modular fixture fixture,such as:(l) General Fixture.Universal fixture refers to the structure,size has been standardized, and has a certain universal fixture.This type of fixture adaptable,can be used to setup the scope of a certain shape and size of various parts.(2)A dedicated fixture.This type of fixture is designed for a particular part of the processing procedures and the design and manufacture.Relatively stable in the product,the production of larger quantities, used a variety of special fixtures,access to higher productivity and machining accuracy.(3)Adjustable fixture.Adjustable fixture for general fixture and special fixture and the defects developed a new kind of fixture.Of different types and sizes of the workpiece,simply adjust or replace the fixture at the original location of the individual components and will be used to clamp components.（4)Modular Fixture. Modular fixture is a modular fixture.Standard components of the module with high precision and resistance to abrasion,can be assembled into a variety of fixtures. Removable fixture used to clean the assembly after the new fixture left.（5) Automatic line fixture.Automatic line clamp generally divided into two categories: fixed-type fixture,which is similar to a dedicated fixture;other accompanying a fixture for the use of the workpiece in the fixture,together with the movement,and
automatic workpiece along the line from a move to the next position position for processing.
2.2Classification by the use of machine tools Classification
By the use of machine tools can be divided into lathe jig fixtures,milling fixtures, drilling fixtures,hang-bed fixture,jig gear machine,CNC machine tool fixture, automatic machine tool fixtures,accompanied by automatic line,and other fixtures, such as machine tools.This is a special fixture design of the classification method used.Dedicated fixture design,the machine group,the type and the main parameters have been determined.Their difference is the cutting forming machine tool movements,so the connection fixture with the machine in different ways.Machining accuracy of their different requirements.
2.3Clamping fixture according to the power source
Clamping fixture according to the power source can be divided into manual fixture, pneumatic fixtures,hydraulic fixtures,gas fixtures by force,electromagnetic fixture, vacuum fixtures,fixture,such as centrifugal force.
3the composition of fixture
Although the structure of machine tool fixture range,but their components can be summarized as the following sections.
(1)Positioning components.Typically,when the shape of the workpiece datum position established,the position will be the basic components of the structure identified
(2)Clamping device.Positioning of the workpiece in the fixture,the need to clamp the workpiece before processing to ensure that the workpiece during processing is not due to external force and undermine its position.
(3)The specific folder.Fixture and the skeleton matrix,all the components through the fixture it will constitute a whole.
(4)Of the knife or the guide.Tool used to determine position relative to the correct position of components.Of the knife device common in milling fixture. Used to adjust the cutter knife block position before machining.
(5)To connect components.Connected components in the machine tool fixture is todetermine the correct position on the component,therefore,can double as a specific folder to connect the fixture on the transition plate,the positioning of milling machine fixture on key components are connected.
(6)Other devices or components.According to the processing needs,some
degree fixture device were used by mode device,the whole device,and the balance of the top block and so on.These components or devices specially designed need.
机床夹具的分类与构成
1机床夹具在机械加工中的作用
夹具是一种装夹工件的工艺装备，它广泛地应用于机械制造过程的切削加工、热处理、装配、焊接和检测等工艺过程中。

在金属切削机床上使用的夹具统称为机床夹具。

在现代生产中，机床夹具是一种不可缺少的工艺装备，对工件进行机械加工时，为了保证加工要求，首先要使工件相对于刀具及机床有正确的位置，并使这个位置在加工过程中不因外力的影响而变动。

为此，在进行机械加工前，先要将工件装夹好。

工件的装夹方法有两种:一种是工件直接装夹在机床的工作台或卡盘上;另一种是工件装夹在夹具上。

采用第一种方法装夹工件时，一般要先按图样要求在工件表面划线，划出加工表面的尺寸和位置，装夹时用划针或百分表找正后再夹紧。

这种方法无需专用装备，但效率低，一般用于单件和小批量生产。

批量较大时，大都用夹具装夹工件。

用夹具装夹工件的优点如下: (l)稳定地保证工件的加工精度。

用夹具装夹工件时，工件相对于刀具及机床的位置精度由夹具保证，不受工人技术水平的影响，使一批工件的加工精度趋于一致。

(2)提高劳动生产率。

使用夹具装夹工件方便、快速，工件不需要划线找正，可显著地减少辅助工时，提高劳动生产率;工件在夹具中装夹后提高了工件的刚性，因此可加大切削用量，提高劳动生产率;可使用多件、多工位装夹工件的夹具，并可采用高效夹紧机构，进一步提高劳动生产率。

(3)扩大机床的使用范围。

在通用机床上采用专用夹具可以扩大机床的工艺范围，充分发挥机床的潜力，达到一机多用的目的。

例如，使用专用夹具可以在普通车床上很方便地加工小型箱体类工件。

甚至在车床上拉出油槽，减少了昂贵的专用机床，降低了成本，这对中小型工厂尤其重要。

(4)改善操作者的劳动条件。

由于气动、液压、电磁等动力源在夹具中的应用，一方面减轻了工人的劳动强度;另一方面也保证了夹紧工件的可靠性，并能实现机床的互锁，避免事故，保证了操作者和机床设备的安全。

(5)降低成本。

在批量生产使用夹具后，由干劳动生产率的提高，使技术等级较低的工人以及废品率下降等原因，明显地降低了生产成本。

夹具制造成本分摊在一批工件上，每个工件增加的成本是极少的，远远小于由于提高劳动生产率而降低的成本。

工件批量愈大，使用夹具所取得的经济效益就愈显著。

2夹具的分类
2.1按夹具的通用特性分类
根据夹具在不同生产类型中的通用特性，机床夹具可分为通用夹具、专用夹具、可调夹具、组合夹具和自动线夹具等:(l)通用夹具。

通用夹具是指结构、尺寸已规格化，而且具有一定通用性的夹具。

这类夹具适应性强，可用来装夹一定形状和尺寸范围内的各种工件。

(2)专用夹具。

这类夹具是专为零件的某一道工序的加工而设计和制造的。

在产品相对稳定、批量较大的生产中，常用各种专用夹具，可获得较高的生产率和加工精度。

(3)可调夹具。

可调夹具是针对通用夹具和专用夹具的缺陷而发展起来的一类新型夹具。

对不同类型和尺寸的工件，只需调整或更换原来夹具上的个别定位元件和夹紧元件便可使用。

(4)组合夹具。

组合夹具是一种模块化的夹具。

标准的模块元件具有较高精度和耐磨性，可组装成各种夹具。

夹具用毕可拆卸，清洗后留待组装新夹具。

(5)自动线夹具。

自动线夹具一般分为两种:一种为固定式夹具，它与专用夹具相似;另一种为随行夹具，使用中夹具随着工件一起运动，并将工件沿着自动线从一个工位移至下一个工位进行加工。

2.2按使用机床分类
按使用机床分类可将夹具分为车床夹具、铣床夹具、钻床夹具、铿床夹具、齿轮机床夹具、数控机床夹具、自动机床夹具、自动线随行以及其他机床夹具等。

这是专用夹具设计所用的分类方法。

设计专用夹具时，机床的组别、型别和主要参数均已确定。

它们的不同点是机床的切削成形运动不同，故夹具与机床的连接方式不同。

它们的加工精度要求也各不相同。

2.3按夹紧的动力源分类
夹具按夹紧的动力源可分为手动夹具、气动夹具、液压夹具、气液增力夹具、电磁夹具、真空夹具、离心力夹具等。

3机床夹具的构成
机床夹具的结构虽然繁多，但它们的组成均可概括为以下几个部分。

(l)定位元件。

通常，当工件定位基准面的形状确定后，定位元件的结构也就基本确定了。

(2)夹紧装置。

工件在夹具中定位后，必须在加工前将工件夹紧，以确保工件在加工过程中不因受外力作用而破坏其定位。

(3)夹具体。

夹具的基体和骨架，通过它将夹具所有元件构成一个整体。

(4)对刀或导向装置。

用于确定刀具相对于定位元件的正确位置。

对刀装置常见于铣床夹具中。

用对刀块可调整铣刀加工前的位置。

(5)连接元件。

连接元件是确定夹具在机床上正确位置的元件因此，夹具体
可兼作连接元件。

车床夹具上的过渡盘、铣床夹具上的定位键都是连接元件。

(6)其他装置或元件。

根据加工需要，有些夹具分别采用分度装置、靠模装置、上下料装置、顶出器和平衡块等。

这些元件或装置也需要专门设计。