模具畢業(yè)設計論文外文翻譯

1、Injectio n Moldi ngThe basic concept of inject ion mold ing revolves around the ability of a therm op lastic material to be softe ned by heat and to harde n whe n cooled .In most op erati ons ,gra nu lar material (the p lastic res in) is fed into one end of the cyli nder (usually through a feeding d

2、evice known as a hopper ),heated, and softe ned( plasticized or pl asticated),forced out the other end of the cyli nder,while it is still in the form of a melt,through a nozzle into a relatively cool mold held closed under pressure.Here,themelt cools and hardens until fully set-up.The mold is then o

3、pen ed,the pi ece ejected,a nd the seque nee rep eated.Thus,the sig nifica nt eleme nts of an injectio n moldi ng machi ne become :1)the way in which the melt is p lasticized (softe ned) and forced in to the mold (called the inject ion un it); 2)the system for opening the mold and clos ing it un der

4、 p ressure (called the cla mping uni t);3)the type of mold used;4)the mach ine con trols.The part of an injectio n-moldi ng machi ne,which con verts a p lastic material from a sold p hase to homoge neousse ni-liguid p hase by rais ing its temp erature .This unit main tai ns the material at a p rese

5、nt temp erature and force it through the injectio n unit no zzle into a mold .The plun ger is a comb in ati on of the injection and p lasticiz ing device in which a heati ng chamber is moun ted betwee n the plun ger and mold. This chamber heats the pl astic material by con ducti on .The plun ger,o n

6、 each storke; pu shes unm elted p lastic material into the chamber ,which in turn forces p lastic melt at the front of the chamber out through the no zzleThe part of an injectio n moldi ng mach ine in which the mold is moun ted,a nd which pro vides the moti on and force to open and close the mold an

7、d to hold the mold close with force duri ng injectio n .This unit can also p rovide other features n ecessary for the effective functioning of the molding operation .Moving plate is the member of the cla mping un it,which is moved toward a stati onary member.the movi ng secti on of the mold is bolte

8、d to this movi ng plate .This member usually in cludes the ejector holesand moldmounting pattern of blot holes or “ T”slots .Stationary plate is the fixedmember of the clamping unit on which the stationary section of the mold isbolted .This member usually includes a mold-mounting pattern of boles or

9、 “ T”slots.Tie rods are member of the cla mping force actuati ng mecha nism that serve as thetension member of the cla mp whe n it is holdi ng the mold closed.They also serve as agutde member for the movable plate .Ejector is a pro visi on in the cla mping unit thatactuates a mecha nism within the m

10、old to eject the molded p art(s) from the mold .Theejecti on actuat ing force may be app lied hydraulically or pn eumatically by a cyli nder(s)attached to the moving plate ,or mechanically by the opening storke of the movingplate.Methods of melting and injecting the plastic differ from one machine t

11、o anotherand are con sta ntly being imp rored .couve nti onal machi nes use a cyli nder and p ist on todo both jobs .This method simp lifies mach ine con struct ion but makes con trol ofinjectio n temp eratures and p ressures an in here ntly difficult p roblem .Other machi nesuse a p lastcat ing ext

12、ruder to melt the p lastic and p isto n to inject it while some harebee n desig ned to use a screw for both jobs :Nowadays,sixty p erce nt of the mach inesuse a rec ip rocati ng screw,35% a plun ger (concen trated in the smaller machi nesize),a nd 5%a screw pot.Many of the problems connected with in

13、 jection molding arises because thedensities of polymers change so markedly with temperature and pressure.Athightemp eratures,the den sityof a polymer is considerably cower than at roomtemp erature ,p rovided thepressure is the same.Therefore,if modls were filled atatmos pheric p ressure,“shrinkage

14、” would make the molding deviate form the shape ofthe mold.To compen sate for this poor effect, molds are filled at high p ressure.The p ressurecomp resses the poly mer and allows more materials to flow into the mold,shri nkage isreduced and better quality moldi ngs are p roduced.Cludes a mold-m oun

15、 ti ng p attern ofbolt holes or “ T”slots.Tie rods are members of the clamping force actuating(1)(8)macha nism that serve as the tension members of cla mp whe n it is hold ing the mold closed.Ejector is a pro visi on in the clami ng unit that actuates a mecha nism within the mold to eject themolded

16、p art(s) form the mold.The ejectio n actuati ng force may be applied hydraulically or pneumatically by a cylinder(s) attached to the moving pl ate,or mecha ni cally by the opening stroke of the moving p late.The fun ctio n of a mold is twofold :im parti ng the desired sha pe to the p lasticized poly

17、 mer and cooli ng the injectio n molded p art.It is basically made up of two sets of components :the cavities and cores and the base in which the cavities and cores are mounted. The mold ,which contains one or more cavities,consists of two basic p arts :(1) a statio nary molds half one the side wher

18、e the p lastic is injected,(2)Am oving half on the clos ing or ejector side of the mach ine. The sep aratio n betwee n the two mold halves is called the parting linen some cases the cavity is partly in the statio nary and p artly in the moving secti on. The size and weight of the molded p arts limit

19、 the nu mber of cavities in the mold and also determ ine the mach inery cap acity required.The mold components and their functions are as followi ng :Mold Base-Hold cavity(cavities) in fixed ,correct position relative tomach ine no zzle .Guide Pin s-Ma in tai n Proper alig nment of en try into mold

20、in trior .Sprue Bush in g(s prue)-Pro vide mea ns of entry into mold in terior .Runn ers-C onrey molte n p lastic from sprue to cavities .Gates-Co ntrol flow into cavities.Cavity(female) and Force(male)-C on torl the size,sha pe and surface of moldarticle.Water Cha nn els-Co ntrol the temp erature o

21、f mold surfaces to chill p lastic torigid state.Side (actuated by came,gears or hydraulic cylinders)-Form sideholes,slots, un dercuts and threaded sect ions.注射成型注射成型的基本概念是使熱塑性材料在受熱時熔融，冷卻時硬 化，在大部分加工中，粒狀材料（即塑料樹脂）從料筒的一端（通常 通過一個叫做“料斗”的進料裝置）送進，受熱并熔融（即塑化或增 塑），然后當材料還是溶體時，通過一個噴嘴從料筒的另一端擠到一 個相對較冷的壓和封閉的模子里。溶里在

22、模腔里冷卻，硬化，直至完 全固化。然后將模子打開，推出工件，并重復以上工序。因此，注塑成型機的重要組成部分是：1）將溶體塑化并擠進進 模腔（稱做“注塑單元”）；2）開模和加壓合模統(tǒng)稱為“合模系統(tǒng)”）； 3）使用上下模具；4）機器控制。注射裝置通過家熱將固態(tài)塑料轉(zhuǎn)化成均勻的半液態(tài)塑體。它保 持塑料當前溫度并加壓使之通過噴嘴進入模具。 柱塞集塑化和注射為 一體。在柱塞與模具之間沒有加熱室，幾熱室通過熱傳導加熱塑料。 每次行程，柱塞將待熔化塑料推入加熱室，依次將熔化的塑料擠到加 熱室前端并通過噴嘴注射出去（注射到模具中去）合模裝置是注射成型機的一個部分，該裝置上安裝有模具。合模 裝置提供運動和動力以

23、開模幾合模，并且在注射過程中提供壓力保持 模具緊閉同時，該裝置還提供成型工藝有效運動所必需的其它特性。 動模板是合模裝置的一部分，在合模時向定模板移動。型腔的運動部 分用螺栓固定在動模板上，動模板通常動模板通常含頂出桿，螺栓空 或T型槽的安裝模具的型板。拉桿是合模力驅(qū)動機構(gòu)中的一個構(gòu)件， 當夾具保持動模閉合時，拉桿起夾具的拉力構(gòu)件的作用。頂出器是合 模裝置的一個部件，它驅(qū)動模具中的執(zhí)行機構(gòu)從模具中頂出成型制 品。頂出力可由液壓或氣動裝置通過裝在動模板上的油（氣）缸來施 加，或者通過動模板開模行程來施加。塑料熔融與塑料注射的方式隨機器的不同而不同 ，并不斷得以改善。常規(guī)的機器采用一個料筒和一個活塞來進行