Chapter 3 Press Process and Die Design（冷冲压工艺及模具）.ppt

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1、Chapter 3 Press Process and Die Design（冷冲压工艺及模具）（冷冲压工艺及模具）Lesson 5 Forming of Sheet MetalsLesson 6 Press Process and Product ApplicationLesson 7 Classification of DiesLesson 8 PressesNEXTChapter 3 Press Process and Die Design（冷冲压工艺及模具）（冷冲压工艺及模具）Lesson 9 Shear OperationLesson 10 Bending OperationLess

2、on 11 Drawing OperationLesson 12 Compound and Progressive DiesPREVLesson 5 Forming of Sheet MetalslSheet metals are generally characterized by a high ratio of surface area to thickness.Forming of sheet metals is carried out generally by tensile forces in the plane of the sheet;otherwise the applicat

3、ion of compressive forces could lead to buckling,folding,and wrinkling of the sheet.lIn bulk deformation processes such as forging,rolling,extrusion,and wire drawing,there is an intentional change in the thickness or the lateral dimensions of the workpiece.However,in most sheet-forming processes any

4、 thickness change is due to the stretching of the sheet underBACKNEXTLesson 5 Forming of Sheet Metalsltensile stresses(Poissons ratio).Thickness decreases should generally be avoided as they could lead to necking and failure.Method of Sheet ShearinglThe shearing process involves cutting sheet metal

5、by subjecting it to shear stresses,usually between a punch and a die much like a paper punch.The punch and die may be any shape;they may be circular or straight blades similar to a pair of scissors.The major variables in the shearing process are:the punch force P,the speed of the punch,lubrication,s

6、urface condition and materials of theBACKPREVNEXTLesson 5 Forming of Sheet Metalslpunch and die,their corner radii,and the clearance between the punch and the die.lIn addition to the shearing processes described above,there are other techniques for cutting sheet metals.The sheet or plate may be cut

7、with a saw,such as a band saw.This is a chip removal process.In another process,called shaving,the extra material from a rough sheared edge is trimmed by cutting(similar to removing a thin layer of wood with a chisel).lFlame cutting is anothercommon method,particularly for thick steel plates.This pr

8、ocess has wide applications in building ships and heavy structural components.BACKPREVNEXTLesson 5 Forming of Sheet MetalslIn friction sawing,a disk or blade rubs against the sheet or plate at surface speeds up to 25000ft/min(130m/s)for disks,and 15000ft/min(80m/s)for blades.In this process,the fric

9、tional energy is converted into heat,which then rapidly softens a narrow zone of the metal.The continuous movement of the disk or blade then pulls the softened metal out of the cutting zone.To help remove the material,some tools have teeth or notches.The friction sawing process is more suitable for

10、ferrous alloys,as nonferrous metals have a tendency to adhere to the disk or blade and interfere with the cutting operation.BACKPREVNEXTLesson 5 Forming of Sheet MetalsNotes:l1.Sheet metals are generally characterized by a high ratio of surface area to thickness.l译文译文:金属板料的金属板料的-般特征是表面积和厚度之间的比率很高。般特

11、征是表面积和厚度之间的比率很高。l解析解析:be characterized by:被赋予被赋予的特征。的特征。a ratio of的比率的比率l2.Forming of sheet metals is carried out generally by tensile forces in the plane of the sheet;otherwise the application of compressive forces could lead to buckling,folding,and wrinkling of the sheet.BACKPREVNEXTLesson 5 Formi

12、ng of Sheet Metalsl译文译文:板料通常通过在板料面上施加拉力来成形板料通常通过在板料面上施加拉力来成形,而如果使而如果使用压缩力就可能导致板料的弯曲、折叠和褶皱。用压缩力就可能导致板料的弯曲、折叠和褶皱。l解析解析:此句为一个用连接词此句为一个用连接词otherwise表转折的复合句表转折的复合句,其中其中前句的主语是现在分词短语前句的主语是现在分词短语forming of sheet metals。l3.However,in most sheet-forming processes any thickness change is due to the stretching

13、of the sheet under tensile stresses(Poissons ratio).l译文译文:然而然而,在大多数板料成形过程中在大多数板料成形过程中,任何厚度的变化都任何厚度的变化都是由于板料在拉应力作用下的延伸是由于板料在拉应力作用下的延伸(泊松比泊松比)。l解析解析:be due to:由于由于,应归于。应归于。BACKPREVNEXTLesson 5 Forming of Sheet Metalsl4.The shearing process involves cutting sheet metal by subjecting it to shear stresse

14、s,usually between a punch and a die much like a paper punch(Fig.5-1).l译文译文:冲裁过程是指在切应力的作用下对板料进行切割冲裁过程是指在切应力的作用下对板料进行切割,通通常是在一个凸模和一个凹模之间常是在一个凸模和一个凹模之间,极似纸张打孔器的操作极似纸张打孔器的操作(图图5-1)。l解析解析:involve:包括包括,涉及涉及,牵连。牵连。subjectw to w:使某人或使某人或某物经历或遭受某事物。某物经历或遭受某事物。l5.In addition to the shearing processes describe

15、d above,there are other techniques for cutting sheet metals.l译文译文:除了上述冲裁过程外除了上述冲裁过程外,还有其他的板料切割方法。还有其他的板料切割方法。l解析解析:in addition to:加之加之,除除之外之外BACKPREVNEXTLesson 5 Forming of Sheet Metalsl6.In another process,called shaving,the extra material from a rough sheared edge is trimmed by cutting(similar to

16、removing a thin layer of wood with a chisel).l译文译文:在另一个被称为缺口修整加工的过程中在另一个被称为缺口修整加工的过程中,通过切割对通过切割对粗糙的冲裁边缘的多余材料进行切边粗糙的冲裁边缘的多余材料进行切边(此过程就像用凿子此过程就像用凿子凿去木材上薄薄的一层凿去木材上薄薄的一层)l解析解析:called shaving前其实省略了前其实省略了which is,合起来是作为合起来是作为修饰中心词修饰中心词another process的定语从句。的定语从句。l7.Flame cutting is another common method,pa

17、rticularly for thick steel plates.This process has wide applications in building ships and heavy structural components.BACKPREVNEXTLesson 5 Forming of Sheet Metalsl译文译文:火焰切割是另一种常见的方法火焰切割是另一种常见的方法,尤其适用于切割厚钢尤其适用于切割厚钢板。这种方法广泛地应用于造船和锻造巨型结构的零件。板。这种方法广泛地应用于造船和锻造巨型结构的零件。l解析解析:have application in:应用于某方面。应用于

18、某方面。l8.In friction sawing,a disk or blade rubs against the sheet or plate at surface speeds up to 25 000ft/min(130 m/s)for disks,and 15 000ft/min(80 m/s)for blades.l译文译文:在摩擦割锯中在摩擦割锯中,锯盘或锯片摩擦表面板料或金属板的锯盘或锯片摩擦表面板料或金属板的速度达到了锯盘为速度达到了锯盘为25 000英尺英尺/分钟分钟(130米米/秒秒),锯片为锯片为15 000英尺英尺/分钟分钟(80米米/秒秒)。l解析解析:rub摩擦。

19、摩擦。rub用于词组中表示用于词组中表示“与与相摩擦相摩擦”,其其后后-定要接介词定要接介词against speed在此句中为动词。句中在此句中为动词。句中up to意为意为“达到达到”。BACKPREVNEXTLesson 5 Forming of Sheet Metalsl9.In this process,the frictional energy is converted into heat,which then rapidly softens a narrow zone of the metal.l译文译文:在此过程中在此过程中,摩擦能转换为热能摩擦能转换为热能,然后热能迅速软化然

20、后热能迅速软化金属板狭窄的部分。金属板狭窄的部分。l解析解析:which引导的是一个非限制性定语从句引导的是一个非限制性定语从句,修饰修饰heato convert:转变转变,转换转换soften:使变软使变软,软化。软化。l10.The friction sawing process is more suitable for ferrous alloys,as nonferrous metals have a tendency to adhere to the disk or blade and interfere with the cutting operation.BACKPREVNEX

21、TLesson 5 Forming of Sheet Metalsl译文译文:摩擦锯割工艺更适合钢铁类合金摩擦锯割工艺更适合钢铁类合金,而有色金属在锯割而有色金属在锯割时则有粘在锯片和刀片上的倾向时则有粘在锯片和刀片上的倾向,以至于妨碍切割过程。以至于妨碍切割过程。l解析解析:be suitable for:适合适合。as在句中的意思为在句中的意思为“因为因为”,等同于等同于because。句中。句中have a tendency to意为意为“有有的倾向的倾向”。BACKPREVLesson 6 Press Process and Product ApplicationslPresswork

22、ing includes a wide variety of chipless processes by which workpieces are shaped from rolled metal sheets.A general term,stamping,is used almost interchangeably with pressworking.lStampings are produced by the downward stroke of a ram in a machine called a press.The ram is equipped with special punc

23、hes and moves toward and into a die block,which is attached to a rigid bed.The punches and the die block assembly are generally referred to as a“die set or,more simply,as the“die.Pressworking operations are usually cold-worked at room temperature or in some casesBACKNEXTLesson 6 Press Process and Pr

24、oduct Applicationslhot-worked at an elevated temperature that does not exceed the annealing temperature of the metal.lParts produced by pressworking operations can be as small as a shoe eyelet or as large as the end of a freight car.Compared to other metalworking processes,pressworking techniques of

25、fer an almost unlimited choice of metals and design versatility and can be produced in extremely large quantities.Metal stampings are lightweight,strong,and have a superior strength-to-weight ratio.It is estimated that the average household contains products in which there are over 100 000 presswork

26、ed items.BACKPREVNEXTLesson 6 Press Process and Product ApplicationslSkillful designers are often able to redesign parts previously made by forging or by casting,with significant savings in time,labor,and materials.Because it is practical to produce parts to close limits of accuracy,interchangeabili

27、ty is assured.lPressworked parts are used for internal components on business machines,machine tools,household equipment,aircraft and small engines,and for locks,various other hardware items,and countless other functional applications.It is estimated that approximately half the weight of an automobi

28、le consists of pressworked parts:Formed parts are widely used as containers ofBACKPREVNEXTLesson 6 Press Process and Product Applicationslvarious kinds,ranging from household pots and pans,to pails,buckets,and bins.Sheet-metal forms are also widely used for heating,exhaust,and ventilating equipment,

29、medical and foodlprocessing equipment,for buildings and structures,household appliances(stoves,refrigerators,freezers,washers,and dryers),bathroom and plumbing and electrical articles,highway vehicles,farm equipment,office furniture,and for many other applications too numerous to mention.BACKPREVNEX

30、TLesson 6 Press Process and Product ApplicationsNotes:l1.Pressworking includes a wide variety of chipless processes by which workpieces are shaped from rolled metal sheets.l译文译文:冲压加工包括多种多样的无屑加工冲压加工包括多种多样的无屑加工,轧制的金属板料轧制的金属板料通过无屑加工后成形为零件。通过无屑加工后成形为零件。l解析解析:a variety of=kinds of多种多样的多种多样的shape:成形成形,做成某

31、做成某种形状种形状;对对有重大影响。有重大影响。l2.The ram is equipped with special punches and moves toward and into a die block,which is attached to a rigid bed.BACKPREVNEXTLesson 6 Press Process and Product Applicationsl译文译文:滑块上装有专门的凸模向装在固定的工作台上的凹滑块上装有专门的凸模向装在固定的工作台上的凹槽运动。槽运动。l解析解析:be equipped with配备有配备有which is attache

32、d to a rigid bed是定语从句是定语从句,修饰中心词修饰中心词a die block。l3.The punches and the die block assembly are generally referred to as a“die set or,more simply,as the“die.l译文译文:这些凸模和凹模装配组件这些凸模和凹模装配组件-般被称为般被称为“模组模组”,或者或者更简单地被称为更简单地被称为“冲模冲模”。l解析解析:refer to:提及提及,谈到谈到;与与有关有关;参考。参考。l4.Pressworking operations are usuall

33、y cold-worked at room temperature or in some cases hot-worked at anBACKPREVNEXTLesson 6 Press Process and Product Applicationslelevated temperature that does not exceed the annealing temperature of the metal.l译文译文:冲压加工的过程常常是在室温下进行的冷加工冲压加工的过程常常是在室温下进行的冷加工,或者或者某些情况下某些情况下,是在不超过被加工金属的退火温度的较高温是在不超过被加工金属的

34、退火温度的较高温度下进行的热加工。度下进行的热加工。l解析解析:cold-worked为合成词为合成词,构词方式为形容词构词方式为形容词cold+过去过去分词分词worked,意为意为“冷加工冷加工”,其反义词为其反义词为hot-worked.l5.Parts produced by pressworking operations can be as small as a shoe eyelet or as large as the end of a freight car.l译文译文:冲压加工出来的零件可以如鞋带孔般小冲压加工出来的零件可以如鞋带孔般小,也可以如运也可以如运货汽车车厢般大。货

35、汽车车厢般大。BACKPREVNEXTLesson 6 Press Process and Product Applicationsl解析解析:as small as:同同一样小。一样小。as.as意为意为“同同一样一样”,表示同级比较表示同级比较,中间的形容词用原中间的形容词用原形。形。l6.Compared to other metalworking processes,pressworking techniques offer an almost unlimited choice of metals and design versatility and can be produced i

36、n extremely large quantities.l译文译文:与其他金属加工工艺相比与其他金属加工工艺相比,冲压技术在金属材料的种冲压技术在金属材料的种类及产品设计方面提供了非常广泛的选择空间类及产品设计方面提供了非常广泛的选择空间,从而利用从而利用冲压技术可以生产大量的产品。冲压技术可以生产大量的产品。l解析解析:compared to other metalworking processes为过去分为过去分词短语作状语词短语作状语,意为意为“与其他金属加工工艺相比与其他金属加工工艺相比”。BACKPREVNEXTLesson 6 Press Process and Product

37、Applicationsl7.Because it is practical to produce parts to close limits of accuracy,interchangeability is assured.l译文译文:由于制出与精确度十分接近的零件是可行的由于制出与精确度十分接近的零件是可行的,所以零所以零件间的互换性是可以保证的。件间的互换性是可以保证的。l解析解析:此句中此句中it为形式主语为形式主语,真正的主语是后面的真正的主语是后面的to produce parts to close limits of accuracy。l8.It is estimated th

38、at approximately half the weight of an automobile consists of pressworked parts.l译文译文:据估计据估计,汽车大约汽车大约-半的重量都是由冲压零件组成的。半的重量都是由冲压零件组成的。l解析解析:it is estimated that:据估计。相同的说法还有据估计。相同的说法还有:it is said that(据说据说);it is reported that(据报道据报道)等等。等等。BACKPREVLesson 7 Classification of DieslDies may be convenientl

39、y classified according to their function:those used to cut metal and those used to form metal.Cutting operations include blanking,trimming,shaving,cutoff,shearing,piercing,slitting,perforating,lancing,extruding,notching,and nibbling.Forming operations include a variety of processes,which are usually

40、 grouped under the general headings of bending or forming or squeezing or drawing.Conventional DieslThese consist of one or more mating pairs of rigid punches and die blocks.Additional auxiliary equipment may beBACKNEXTLesson 7 Classification of Diesladded to increase the pressworking versatility.Co

41、nventional dies include single-operation or simple dies,compound or combination dies,progressive dies,transfer dies,and multiple dies.lSome die sets are designed to perform a single pressworking operation,which may include any of the operations listed under cutting or forming.Such dies are called si

42、ngle-operation dies or simple dies.Oneoperation is accomplished by a single stroke of the press.Fig.7-1 illustrates a simple die for trimming a horizontal flange on a drawn shell.In this example,the workpiece is positioned on a locating plug.After the ring-shaped scrap from aBACKPREVNEXTLesson 7 Cla

43、ssification of Dieslsufficient number of trimmed shells has accumulated,a scrap ring at the bottom is severed with each stroke of the press by the scrap cutter and fialls clear.Compound or Combination Dies These will be used when two or more operations are performed at one station.lFig.7-2 illustrat

44、es a part that was formed by one stroke of the press in a compound die.In this example,the dished washerwas simultaneously blanked,pierced,and formed.In mass-production operations compound dies are more economical than a series of single operation dies,and they are usually more accurate.BACKPREVNEXT

45、Lesson 7 Classification of DiesProgressive DieslThese are used for high-production applications.In this case coil stock or flat strip is fed from station to station.The die performs work at some or all of the stations during each press stroke.When all the work has been completed,the work is cut off

46、and unloaded.Fig.7-3 shows an adapter ring that was produced in a five-station progressive die.Progressive dies are generally expensive to construct.In addition,the cost of the required auxiliary equipment is high.Progressive dies are usually set up on automatic presses with a scrap cutter,feeder,st

47、raightener,and uncoiler.BACKPREVNEXTLesson 7 Classification of DiesTransfer DieslThese are used to produce parts which,because of their general configuration,are difficult to feed from station to station in progressive dies.Individual precut blanks are first prepared by feeding coil stock into a pre

48、ss.Additional cutting and forming operations on the separate workpiece blanks are then performed by mechanically feeding each blank from station to station.Like progressive dies,transfer dies and their related equipments(presses,special attachments,and feeding devices,etc)are expensive.Their use is

49、recommended only in cases of high-quantity production.BACKPREVNEXTLesson 7 Classification of DiesMultiple DieslThese are also used in mass production.Such dies produce two or more workpieces at each stroke of the press.It is possible to produce pairs of right-hand and left-hand parts,duplicate parts

50、,or unrelated parts.Multiple dies may consist of two or more single-operation dies or multiples of compound dies.Advantages of multiple dies may include savings in material resulting from more efficient blank layout,and reduction of labor costs.The leading disadvantages are increased costs in die co