制造技術(shù)基礎(chǔ)復(fù)習(xí)基本概念與基本原理英語表達(dá).doc

1 10 制造技術(shù)基礎(chǔ)復(fù)習(xí)基本概念 基本原理英語表達(dá)參考 Review the Basic Concepts and Principles of Fundamentals of Manufacturing Technology in English CHAPTER ONE DESIGN FOR MECHANICAL PROCESS PLANNING Section 1 Basic concepts Production procedure of mechanical products Process procedure of machining Elements of Process procedure of machining 1 sequence 工序 2 installation 安裝 3 station 工位 4 step 工步 5 pass 走刀 Sequence process procedure that consists of several sequences during which workers operate on the works continuously in the same place 操作者 加工地 工作對(duì)象 人為劃分 相對(duì)可變 Installation in a sequence if the work is required to put into position and clamp several times the part of sequence done in one positioning and clamping is called an installation 確定 Station In an installation by using the indexing or moving device the work is changed its position relatively to the cutting tool All the tasks done for the work in one machining position in an installation is termed as the station 確定 Step In one station if the surface cut cutting tool velocity and feed remain unchanged these working contents are thought of as the step 加工表面 刀具 切 削速度 進(jìn)給量任一改變均為另一工步 Pass When the surface of the work is cut for any one time such task carried out is named as the pass 2 10 刀具在加工表面的每一次切削 Processing system a system that contains the work to be machined fixture that holds the work in the proper position cutting tool that machines the work directly and machine tool that gives the power and provide the movements to accomplish the processing In recent years the gauging and measuring is added to the system Relationship between the batch and the pattern of production N program of production Q annual turnout of the product n number of the components a year share rate waste rate F annual working days A number of days for inventory number of components in a lot A Program of production In a period of planning the turnout of product and schedule to be fulfilled is called program 計(jì)劃期的產(chǎn)量加進(jìn)度 生產(chǎn)綱領(lǐng) The turnout in one year planning is named the annual program B Batch of production At a time the number of identical products to be put into production or to be produced is termed as batch of production 一次投入生產(chǎn)的同一產(chǎn)品的數(shù)量 生產(chǎn)批量 Process planning for machining operations stipulated document for technological process 機(jī)械加工工藝規(guī)程 以工藝文件形式規(guī)定的機(jī) 械加工工藝過程 Patterns of the process planning for machining Generally speaking the process planning for machining appears in the form of sheet or card with the same basic content in three patterns Pattern A sheet of process procedures 工藝過程卡 a very simple and concise document usually for single small batch production Pattern B sheet of process operation 機(jī)械加工工藝卡 often for batch production Pattern C sheet of process sequence 機(jī)械加工工序卡 with detailed and complete contents frequently for massive production Section 2 Location and Datum of the work in machining Installation and clamping 裝夾 concerning about the ways in which the work is installed and clamped in the fixture or on the machine tool including two aspects locating 定位定位 and clamping 夾緊夾緊 Locating the procedure during which the work gains its proper position in the fixture or on the machine tool Clamping when the workpiece has gained its correct position in the fixture it will be subject to the external forces while being machined So to hold or keep the workpiece in the correct position is definitely required which is called clamping Six Point Locating Principles A cuboid is in cartesian coordinate with six degrees of freedom 1 N Qn b N F n A 3 10 The six degrees of freedom are three linear movements along the three coordinate axes respectively and three rotations around these coordinate axes In theory the locating point is the geometric point in reality it is something different with its three dimensions The following are commonly used in workshops Button locator 支撐釘 Plug 檔銷 Supporting plate 支撐板 Pin pin locator 長(zhǎng)銷 Button Cut pin rhombus pin 削邊銷 菱形銷 Mandrel 心軸 V block 形塊 Short V block 短形塊 Positioning sleeve 定位套 Fixed floating conic pin 固定 浮 動(dòng)錐銷 Center 頂尖 固定 浮動(dòng) Complete positioning locating with constraint for all six degrees of freedom Incomplete positioning locating with constraint for less than six degrees of freedom Under over positioning the number of constraints of degree of freedom is less than that required Under positioning ought to be avoided and Over positioning the same degree of freedom is constrained by two or even more constraining points such situation is called over positioning which will be allowed occasionally Datum 基準(zhǔn)基準(zhǔn) is the point line or surface based on which the geometric relation ships among geometric elements of the object to be worked at are determined The concept is so important that is may be used for any aspect of production from design through manufacturing including sequences of operation to the gauging and assembly Technological process datums Sequential datum on the sequential drawing datum that is used in this sequence to determine the size form and position of the work after being machined is named Sequential datum The three aspects are supposed to be taken into consideration the priority of sequential datum is paid to the design datum that is use the design datum as sequential datum the selected datum is favorable for the location and the gauging of the work and if the above requirements are hardly met the datum used to guarantee the technical conditions Datum may be classified into two categories Design datum and Technological datum according to their functions I design datum in design of components the origin from which according to the assembly relationship of the component and the relative relationship of the structural elements of the component itself the dimensioning is done These original positions are called design datums 設(shè)計(jì)圖紙上零件標(biāo)注的起始位置設(shè)計(jì)圖紙上零件標(biāo)注的起始位置 II technological datum datum used in the process operations is termed technological datum which can be even classified as Locating datum datum used for the workpiece to gain its proper position in machining it directly influences the effectiveness of machining Locating datum covers Rough datum and Finishing datum a Rough datum Finishing datum un machined locating datum in other word any locating datum used in the first sequence of operation in the manufacturing process planning is the rough datum finishing datum machined locating datum b additional auxiliary datum the specially designed datum in the workpiece because of the requirement of the mechanical process operations Gauging datum during and after machining datum used for measuring and checking the form position and error of size of the workpiece Assembling datum in assembling datum adopted to determine the relative positions of the work or the component in the product X Y and Z X Y and Z 4 10 Section 3 Design of the routes of machining processes 工藝路線的制定 工藝路線的制定 Consideration must be taken with the locating datum of the workpiece 定位基準(zhǔn) the process methods 加工方法 the order of the processes 加工順序 heat treatment 熱處理 testing 檢驗(yàn) and the related operations 其他工序 A selection of locating datums 定位基準(zhǔn)的選擇 B selection of economic accuracy and process methods of machining 機(jī)加的經(jīng)濟(jì)精度與方法 C machining routes for the typical surfaces 典型表面的加工路線 外圓 孔和平面 D order of sequences 工序順序安排 Selecting rules of rough machining datum I guarantee the proper relative positions II guarantee reasonable allocation of the allowance for the surface being machined III facilitate the locating and clamping of the workpiece For this reason the selected surfaces as the datums must be to some extent smooth enough sized flasher free without other defects such as reservoir and riser or the like IV the rough locating datum used only for one time without repetition Selecting rules of finishing machining datum I overlapping principle 基準(zhǔn)重合 datum used as the same as design datum II unifying principle 基準(zhǔn)統(tǒng)一 use the same datum as early and as frequently as possible III inter reference principle 互為基準(zhǔn) especially used for the high accuracy of relative positions of the surfaces IV self reference principle 自為基準(zhǔn) for sequence of small roughness small and even allowance V clamping facilitating convenient principle 便于裝夾 for proper and secure reliable locating simple structure of the clamping device with easy operation Economic accuracy in machining 經(jīng)濟(jì)加工精度經(jīng)濟(jì)加工精度 Under the common machining conditions that is with facilities and tooling in standard quality the operators with typical skills and in rated time the machining is done with the relevant accuracy and roughness imparted to the component Such accuracy and roughness is called the economic accuracy in machining Order of sequences 工序順序安排 a datum first then others b flat first then others generally c the main surfaces first d rough machining first followed by finishing machining Centralized decentralizes sequences and the Machining stages I rough machining II semi finishing machining III finishing machining IV precision ultra precision and smooth machining Section 4 Determination of machining allowance dimensions between sequences and tolerance machining allowance the difference between the size of the blank and that of the component design on drawing the total allowance is equal to the sum of material thickness to be removed for every step in the process operation Sequential allowance the thickness of metal removal of the cut layer in every sequence The relationship between the total allowance and Sequential allowance will be expressed in terms of Zo Z1 Z2 Zn n i i 1Z 5 10 CHAPTER TWO DESIGN PRINCIPLES OF MACHINE TOOL JIGS AND FIXTURES Section 1 introduction to the machine tool jigs and fixtures Function constituents and classification 夾具的功用 組成和分類 夾具的功用 組成和分類 Function the machine tool jig or fixture is a device used in machine tool by which the workpiece obtains and keeps the proper position relative to the machine tool before and during the workpiece being machined Constituents of the fixture Six elements or units of a jig or fixture I locating elements for locating the work such as button locator base body and rhombus II tool guide for guiding the tool or adjusting relative position of the tool to the fixture such as tool setting block III clamping device for holding the work firmly such as the bolt screw and the heel IV connecting elements for determining the position of the fixture on the machine tool and connecting the fixture with the machine tool such as the locating key and the base V body for connecting all the elements and devices as a whole and through the body the fixture being fixed to the machine tool such as the base VI additions for other purposes like indexing safeguarding error avoiding and the like such as the stop pin Classification of the fixture According to the range of usage fixtures can generally be classified into six categories all purpose special all purpose adjustable and group composite transferring fixtures In accordance with the machine tool on which the fixture is utilized fixtures can also be classified into lathe milling machine drill borer grinder automatic machine tool and NC machine tool fixtures Based on the power which drives the clamping devices to hold the work firmly in place fixtures can even be classified into manual pneumonic hydraulic electric magnetic and vacuum fixtures Section 2 Workpiece location in the fixture the analysis and calculation of locating error Commonly used methods of locating and the locating elements the surfaces of the workpiece A locating by flat plane surface 平面定位 Fixed adjustable self adapted auxiliary support 固定 可調(diào) 自位 輔助支承 Section 3 Workpiece clamping in the fixture Requirements of the clamping forces Determination of the clamping forces Commonly used clamping mechanisms Requirements of the clamping forces I sustain during the whole period of clamping the proper position of the workpiece when it locates II be reliable and proper The clamping mechanisms are usually supposed to have the function of self locking guaranteeing the clamping device being free from relief and vibration On the other hand preventing ought to promise from being unwanted deformation and the damage of the surfaces III It is taken for grant that the clamping device is convenient not energy consuming and safe to operate IV be consistent for the complexity and level of automation of the clamping device with the batch production and the pattern of production 6 10 A Direction The following rules should be ensured favorable for the workpiece locating Parallel to the direction of the most rigid of the work Preferable to parallel to the direction of the cutting forces or the gravity of the work to reduce the clamping force B Exerting point under the given force to select the point at which the clamping force actuates and the number of the exerting points I the exerting point coincides with the supports of the fixture or is on the supporting area backed by the supports II the exerting point ought to be so set that the touched area has great rigidity of the work in order to reduce the deformation of the work possible to occur III It is preferable to exert the clamping force at the as near place of the being cut surface as possible to eliminate the turn over moment by the cutting forces C Magnitude of the clamping forces Section 4 types of machine tool mixtures Drill jigs Borer jigs Milling machine fixtures Lathe fixtures Group fixtures Composite fixtures Transferring fixtures CHAPTER THREE MECHANICAL PROCESS ACCURACY 1 Concept of the machining accuracy and the influencing factors 2 Geometric accuracy influencing the machining accuracy 3 Deformation of the processing system from external forces 4 Deformation of the processing system caused by heat 5 Statistics and analysis and ways of guaranteeing and enhancing the machining accuracy Section 1 Brief introduction to Machining Accuracy The quality of a component by machining contains two fold one is Mechanical Process Accuracy and another is the Integrity of Machined Surfaces Here we discuss the first aspect of the quality of the component Mechanical process accuracy is the degree of the real geometry including the size form and relative position between surfaces of a workpiece imparted by machining that approaches the perfect geometry Influencing factors of machining accuracy 1 Installation of the workpiece 工件的裝夾 installing error of the workpiece 工件裝 夾誤差 2 Adjustment of the processing system 機(jī)床 刀具和夾具的調(diào)整 geometric error of the processing system 工藝系統(tǒng)幾何誤差 3 Machining operation 加工過程 dynamic error 動(dòng)誤差 Sensible direction of the error on the workpiece the initial errors vary both in magnitude and in direction when the direction of initial error is parallel to that of the sequential size such error has the greatest influence on the machining accuracy So we call this direction Sensible direction of the error Section 2 The influence of geometric accuracy of the processing system on the machining accuracy A error of principle in machining 加工原理誤差 B error of adjustment 調(diào)整誤差 C error of machine tools 機(jī)床誤差 7 10 Guiding error of the guide way For a linear guide way the guiding accuracy includes linearity on the horizontal plane y linearity on the vertical plane z parallelism between the two guide ways warp 扭曲 and the parallelism between the guide way and the axis of the spindle Rotating error of the spindle Notion rotating accuracy of the spindle is one of the main aspects of accuracy Rotating accuracy of the spindle influences mainly the accuracy of geometric form position and roughness of the machined surfaces because of its function of installing and clamping the work or tool and providing the primary power and machining movement Rotating error of the spindle is the real floatation drift of the rotating axis from the perfect rotating axis of the spindle including radial round flounce facial round flounce and inclined angular swing and transmitting error of the transmission linkage D error of the fixture in its own production and wear 夾具制造誤差與磨損 E error of the tool in its own production and wear 刀具制造誤差與磨損 Section 3 Deformation of the processing system from external forces Basic concept in machining any element or all the elements of the processing system may be subjected to cutting force clamping force and weight leading to deform and further cause machining errors The ability to resist the deformation is often expressed in terms of rigidity k 剛度 of the system which means the ratio of the normal component of the cutting force to the displacement of the work in the direction of the normal component of the cutting force Section 4 Deformation of the processing system caused by heat a Notion of the deformation from heat and the heat balance and temperature distribution b Influence of the deformation of the work from heat on machining accuracy c Influence of the deformation of the tool from heat on machining accuracy d Influence of the deformation of the machine tool from heat on machining accuracy e Ways of reducing the influence of the deformation from heat on the machining accuracy Origin of the heat Internal heat source mainly the cutting force and friction forces with the conductivity External heat source mainly the environmental temperature with circulation as well as heat radiating sources The cutting force is the main and important source of heat The heat balance and the temperature field Qgeneration Qtakein Qgoingout x y z t x y z deformation x y z Ways of reducing the influence of the deformation from heat on the machining accuracy 1 Reducing the heat from the heat source and keeping free from the heat source 2 Evening the temperature field distribution 3 Adopting the proper structure and assembling datums of the machine tool 4 Speeding up the procedure of heat balance 5 Controlling the surrounding temperature Section 5 Statistics and analysis and ways of guaranteeing and enhancing the machining 8 10 accuracy a System error In machining a batch of components successively if the magnitudes and directions of machining errors remain unchanged or change regularly we call these e