2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
已閱讀1頁,還剩13頁未讀, 繼續(xù)免費閱讀

下載本文檔

版權(quán)說明:本文檔由用戶提供并上傳,收益歸屬內(nèi)容提供方,若內(nèi)容存在侵權(quán),請進行舉報或認(rèn)領(lǐng)

文檔簡介

1、<p><b>  英文原文</b></p><p>  Injection molding machine</p><p>  Injection molding machine is plastic machine for short. It uses the thermal physical properties of plastics, the ma

2、terial from the hopper into the barrel, is barreled by heating coil heat, so the material will be melted, which is arranged by the external force under the action of the motor driving the rotation of the screw in the bar

3、rel. The material in the screw under the action of the screw groove, along the forward delivery and compaction, dual role the material in the heating and shear under</p><p>  Configuration according to the c

4、lamping member and the injection component type has horizontal, vertical, angle type three</p><p>  (1) Horizontal injection molding machine: horizontal injection molding machine is the most common type. Its

5、 characteristic is the center line injection assembly and clamping assembly center line of concentric or consistent, also with the parallel to the mounting surface. It has the advantages of low center of gravity, steady

6、work, mold installation, operation and repair, which are convenient, the mold opening big, small occupied space height; but covers an area of large. </p><p>  (2) Vertical injection molding machine: its char

7、acteristic is clamping device and injection device of the axis line arrangement and perpendicular to the ground. It also has the advantages of small occupied area, convenient assembly and disassembly of insert mold, easy

8、 installation, since the bucket into the material plasticization is evenly, easy to realize automation and machine automation line management. The disadvantage of it is the top product is not easy to fall off automatical

9、ly, it often</p><p>  (3) Angle type injection molding machine: injection device and a molding device axis are arranged vertically. According to the injection assembly center lines are vertical, horizontal a

10、nd relative position of the vertical and horizontal installation, recumbent points: ① horizontal vertical, injection assembly line and plane parallel, and mold assembly center line and the base of vertical and horizontal

11、, vertical; injection assembly center line and the surface vertical, and die assembly center li</p><p>  At present, the injection device are common cylinder form and double cylinder form, I plant the inject

12、ion molding machine is double cylinder form, and is directly driven by a hydraulic motor of screw in injection molding. Because of different manufacturers, different types of machine components are not the same; the foll

13、owing will make a concrete analysis of our factory with machine.</p><p>  The working principle is: the plastic, screw in plastic parts in the drive the main shaft to rotate through the hydraulic motor, spin

14、dle end is connected with the screw, and the other end of the hydraulic motor key connection, screw rotation, plasticity and melt classified pushed to the storage chamber cylinder front, at the same time, screw back in t

15、he reaction material, and through the thrust bearing the thrust seat back, pulling the piston rod through the nut straight back. To complete the me</p><p>  The work principle of screw plasticizing component

16、s: performs, screw rotation, from the material inlet into the screw groove material advancing continuously forward, heating ring through the barrel wall of the heat transfer to the spiral groove material, solid material

17、in the dual role of external heating and screw rotational shear, and through the thermal process functional section of screw, achieving the plasticizing and melting, melting away the check ring around the screw head, fro

18、nt end thr</p><p>  Screw plasticizing components generally have the following characteristics:</p><p>  The screw has two functions of plasticizing and injection;</p><p>  The scre

19、w in plastic, only for the plastic</p><p>  The plastics in plasticizing process, thermal process through than extrusion;</p><p>  The screw on the plasticizing and injection were to occur, axia

20、l displacement, and screw in working state of intermittent when to stop, thus forming a non - stability of screw plasticizing process.</p><p><b>  (1) Screw</b></p><p>  Screw is a k

21、ey component of plastic parts, direct contact with plastic, plastic through the effective length of the screw channel, after the heat for a long time, must go through 3 states (glass, behavior, viscous state) transformat

22、ion, geometric parameters, geometry, length of functional section of screw will directly affect the transmission efficiency and the plasticizing quality of plastic, will ultimately affect the quality of injection molding

23、 cycle and product.</p><p>  Compared with the extrusion screw, plastic screw has the following characteristics:</p><p>  The injection screw length-diameter ratio and compression ratio is small

24、;</p><p>  Screw groove of injection screw is section of the deep;</p><p>  The injection screws feeding sections is longer, and are short;</p><p>  The injection screw work, plasti

25、cizing capacity and melt temperature will vary with the axial displacement screw and change.</p><p>  (I) classification, screw</p><p>  Injection screw according to the plastic adaptability, ca

26、n be divided into general and special screw, general also called conventional screw, can be processed with low viscosity, most of the thermoplastic, civil plastic crystalline and amorphous and engineering plastics, is th

27、e most basic form of the screw, and the corresponding and special screw, is used to process with ordinary screw processing hard plastic; according to the screw structure and geometry characteristics, can be divided into

28、con</p><p>  The conventional screw thread effective length is usually divided into feeding sections (conveying), the compression section (Plastics segment), and metering section (averaging period), accordin

29、g to the plastic properties of different, can be divided into gradual, mutation type and general type screw.</p><p>  The tapered screw: compression long, plasticizing energy transfer for PVC relaxation, poo

30、r thermal stability of plastic.</p><p>  The mutant compression screw: short, plasticizing energy conversion is more acuteness, used for polyolefin, PA crystalline plastics.</p><p>  The general

31、 purpose screw: adaptability is strong, and can be suitable for processing a variety of plastic, avoid frequent replacement of the screw, increase production efficiency.</p><p>  DS screw diameter, screw dia

32、meter directly affect the plasticizing capacity, will directly affect the injection volume, therefore, injection volume of injection molding machine the screw diameter is large.</p><p>  L/ds - screw length

33、to diameter ratio. L is the effective length of screw thread part of the screw, the ratio of length to diameter is larger, the length of that thread, directly affect the thermal process of material in the screw, the abil

34、ity to influence the absorption of energy, while the energy source has two parts: one part is the external heating coil to the barrel, and another part is friction thermal and shear heat generated by the rotation of the

35、screw, the external mechanical energy co</p><p>  L1 - feeding length. The feeding section is also called conveying or feed section, in order to improve the transport capacity, screw groove surface must be s

36、mooth, the length of the L1 shall ensure that the material conveying length too short enough, because L1 will lead to premature melting material, thus it is difficult to guarantee the transportation conditions of stabili

37、zing pressure, will be difficult to ensure the screw later. Plastic under their own gravity from the hopper to slip into th</p><p>  The depth of screw channel H1 - feed section. H1 deep, is receiving materi

38、als, improving the feeding quantity and plasticizing capacity, but will affect the shear strength of material plasticization and screw root, general H1 ≈ (0.12 ~ 0.16) ds.</p><p>  L3 - melting length. Melti

39、ng section called homogeneous section or the measuring section, melt further homogenization, uniform temperature in the channel of L3 segment, uniform composition, the formation of good quality of melt, the length of L3

40、is helpful to melt in the screw groove fluctuations, stable pressure, causes the material to feed evenly extruded from the screw head, so it is also called the metering section. L3 short time, help to improve the general

41、 screw plasticizing capacity, L3= </p><p>  H3 - melting section of spiral groove depth, H3 small, shallow groove, improves the plasticizing effect of plastic melt, to melt homogenization, but H3 is too smal

42、l will lead to higher shear rate, and shear heat is too large, causing degradation of the molecular chain, the effect of melt quality,; conversely, if the H3 is too large, the perform, enhanced flow screw back pressure g

43、enerated, will reduce the plasticizing capacity.</p><p>  L2 - plasticizing period (compression) length of thread. The tapered space material continuously under compression, shear and mixing effect, material

44、 from the L2 point, molten pool increased, to the point of weld pool has been occupying the entire screw groove, the material from the glass state through viscoelastic state transition to a viscous state, namely this seg

45、ment, the plastic is state of coexistence in the particles with a molten body. The length of L2 will affect the transformation of t</p><p>  S - Pitch, the size effect of helix angle, thus affecting the tran

46、sport efficiency of screw, general S ≈ ds.</p><p>  E - Compression ratio. ε =h1/h3, namely the feeding section of spiral groove depth H1 and the melting section of spiral groove depth ratio of h3. E, will e

47、nhance the shear effect, but will weaken the plasticizing capacity, generally speaking, ε slightly smaller as well, to help improve the plasticizing capacity and increase the adaptability to raw materials, for crystallin

48、e plastics, the compression ratio is 2.6~3.0. For low viscosity and thermal stability of plastic, can choose the high compres</p><p>  (2) The screw head</p><p>  In the injection screw, screw h

49、ead is: the plastic, can be good plastic melt and releasing to the storage chamber, and in high pressure injection, and can effectively close the melt front screw head, prevent backflow.</p><p>  The screw h

50、ead is divided into two categories, with check ring and not the inverse ring with the check, the check ring, a plastic screw, melt homogenizing section will check ring away, through the gap formation and the screw head,

51、into the storage chamber, injection pressure, melt screw the head of the formation of thrust, the non-return valve return channel plugging, prevent backflow.</p><p>  For some high viscosity materials such a

52、s PMMA, PC, AC or poor thermal stability of PVC material, in order to reduce the retention time of shearing and material, can not check ring, but this injection will produce reflux, prolonging holding time.</p>&l

53、t;p>  On the screw head requirements:</p><p>  The screw head to be flexible smooth;</p><p>  The check ring and the cylinder to be suitable with the gap, to prevent melt flow, and flexible;&

54、lt;/p><p>  The existing flow section is enough, but also to ensure the check ring face a return force, making fast closed at the time of injection;</p><p>  The structure should be easy disassembl

55、y, convenient cleaning;</p><p>  The direction of the screw thread screw and screw in screw head instead, prevent a plastic screw head loose.</p><p>  (3) Cylinder</p><p>  (I), the

56、 barrel structure</p><p>  Cylinder is an important part of plastic parts; interior screw is arranged outside the heating coil, under complex stress and thermal stress.</p><p>  (II), the feedin

57、g port</p><p>  Structure feeding port directly affects feed effect and plastic parts of the feeding ability, injection molding machine most by gravity feed material in hopper, simple manufacture, but feed t

58、he negative; the feed material and the screw contact angle, contact area is large, can improve the feed efficiency, is not easy in the hopper into bridge hole.</p><p>  (III), cylinder wall thickness</p&g

59、t;<p>  Cylinder wall thickness is of sufficient strength and stiffness, because the barrel to melt and gas pressure, and the barrel length to diameter ratio, cylinder requires enough heat capacity, so the cylinde

60、r walls have a certain thickness, otherwise it is difficult to ensure that the temperature stability; but if it is too thick, barrel bulky, waste material, the thermal inertia of large, slow temperature rise, temperature

61、 regulation of delay larger.</p><p>  (IV), cylinder clearance</p><p>  Cylinder gap refers to the single gap barrel wall and screw diameter, the gap is too large, plasticizing capacity is reduc

62、ed, injected back into the discharge increases, injection time, causing material degradation in the process; if it is too small, the thermal expansion effect on the screw and barrel friction, energy consumption increased

63、, even death card, this gap delta = (0.002~0.005) ds.</p><p>  (V), the material heating and cooling tube</p><p>  Injection molding machine barrel heating with electric resistance, ceramic heat

64、ing, cast aluminum heating, should be reasonably arranged according to the application and processing of materials, commonly used has the resistance heating and ceramic heating, to comply with the requirements of injecti

65、on molding process, the barrel to subsection control, small 3, large machine 5.</p><p>  Cooling refers to the feeding mouth is cooling, because the feeding mouth if the temperature is too high, the solid in

66、 the feeding mouth "bridge", blocking the outlet, thus affecting the transport efficiency of feed section, so the cooling water jacket is arranged in the cooling it. Our factory is through the cooling circulati

67、ng water cooling of the feed inlet.</p><p>  (4) Nozzle</p><p>  (I) function of spray nozzle</p><p>  The nozzle is an important part of connecting plasticizing device and mold flo

68、w; nozzle has a variety of functions:</p><p>  The perform, establishment of backpressure, degassed, prevent melt salivation, improve plasticizing capability and measurement precision;</p><p>  

69、The injection mold, forming the contact pressure and the main cast, keep good contact with pouring nozzle sleeve, forming a closed channel, to prevent the plastic melt under high pressure overflow;</p><p>  

70、injection, establish the melt pressure, shear stress, and the pressure head into the velocity head, the increase of shear rate and temperature, enhance mixing and homogenizing;</p><p>  Changing the nozzle s

71、tructure to match the mold and plasticizing device, a new type of flow channel or injection system;</p><p>  The nozzle also bears the thermostat, thermal insulation and cutting function;</p><p>

72、;  The reducing melts in the import and export of the viscoelastic effect and the eddy loss, in order to stabilize its flow;</p><p>  The holding pressure, easy to mold products of feeding, and the cooling s

73、haping increased reflow resistance, reduce or prevent the melt in the cavity to return.</p><p>  (II) The basic form, nozzle</p><p>  Nozzle can be divided into straight-through nozzle, locking

74、type nozzle, hot runner nozzle and the flow nozzle, the present stage our factory are straight-through nozzle.</p><p>  Straight-through nozzle is the nozzle is widely applied, its characteristic is the dire

75、ct and main casting mold nozzle spherical contact, the nozzle radius and the channel than the mold to be small, injection pressure, melt directly through the mold runner system is filled into the cavity, fast speed, low

76、pressure loss, manufacturing and installation are all relatively convenient.</p><p>  Locking type nozzle is mainly to solve the problem through the nozzle salivation, suitable for low viscosity polymer (suc

77、h as PA) processing. In the closing the nozzle plastic, prevent melt salivation phenomenon, and when the injection and injection pressure to open, so that melt into the mold cavity.</p><p>  2 injection cyli

78、nder</p><p>  Its working principle is: the injection cylinder into the oil, the piston drives the piston rod and the bearing is arranged on the thrust seat, drive screw</p><p>  Push the screw

79、forward or backward. Through the nut piston rod head, can adjust the timing of two parallel to the axial position of the piston rod and the injection screw axial position.</p><p>  3 thrust bearing</p>

80、<p>  Injection, thrust bearing thrust shaft driven by screw injection; while the plastic, the oil motor drive screw rotation to achieve thrust shaft drives the perform.</p><p>  4 cylinders</p>

81、<p>  When a moving oil cylinder into the oil, forward seat injection or the back action, and to ensure the injection nozzle and mould the main cast set of circular arc closely contact, the injection pressure can

82、seal the melt.</p><p>  The 5 part accuracy requirements for injection</p><p>  After the assembly, the components are arranged on the machine frame, must ensure that the nozzle and mold water s

83、leeve is tightly bonding, in order to prevent overflow, the center line of injection parts requirements and the clamping parts of the center line of concentric; in order to ensure the accuracy of injection screw and barr

84、el inner hole, must ensure that the two injection cylinder bore and the center cylinder hole is parallel with the center line of symmetry; in the horizontal plane, pa</p><p>  Each kind of plastic, has an id

85、eal plastic processing temperature range, should control the processing temperature of barrel, which is close to the temperature range. Granular plastic from the hopper into the barrel, the first will arrive at a feeding

86、 section, in the feeding section will appear dry friction, when the plastic is heated, melting is not uniform, very easy to cause the barrel wall and screw wear surface. Similarly, the compression section and the entire

87、segment, if the molten state </p><p>  Speed should be adjusted properly. The friction force of these substances on the metal material is often much larger than the molten plastic. In the plastic injection m

88、olding, if using high speed in the shear stress on the plastic at the same time, it will also strengthen correspondingly more torn fibers, the torn fibers containing sharp end, to wear a large force to increase. Inorgani

89、c minerals on the surface of metal high-speed taxiing, the scraping is not a small role. So the speed should not</p><p>  In addition to check in plastic debris, the original purchase fresh plastic and no de

90、bris, but after weighing, transport, drying, mixing, especially to add recycling back material, there may be mixed with debris. Small as metal filings, as big as a heating ring nut clip, or clusters of warehouse key, mix

91、ed into the barrel had occurred, the screw damage is self-evident. (barrel of course also damage), therefore must install the magnetic iron material, strict management and monitoring.</p><p>  Moisture in pl

92、astics has a certain effect on the wear surface of the screw. If the plastic in injection unprecedented will eliminate all residual moisture, moisture into the screw compression section, they formed before melt blend in

93、molten plastic with high temperature and high pressure "steam particles", with the injection process screw propulsion, from homogeneous section until the screw head, these "steam" particle, pressure d

94、rop and expansion in the injection process, the impurities such as</p><p><b>  中文譯文</b></p><p><b>  注塑成型機</b></p><p>  注塑成型機簡稱注塑機。注塑成型是利用塑料的熱物理性質(zhì),把物料從料斗加入料筒中

95、,料筒外由加熱圈加熱,使物料熔融,在料筒內(nèi)裝有在外動力馬達作用下驅(qū)動旋轉(zhuǎn)的螺桿,物料在螺桿的作用下,沿著螺槽向前輸送并壓實,物料在外加熱和螺桿剪切的雙重作用下逐漸地塑化,熔融和均化,當(dāng)螺桿旋轉(zhuǎn)時,物料在螺槽摩擦力及剪切力的作用下,把已熔融的物料推到螺桿的頭部,與此同時,螺桿在物料的反作用下后退,使螺桿頭部形成儲料空間,完成塑化過程,然后,螺桿在注射油缸的活塞推力的作用下,以高速、高壓,將儲料室內(nèi)的熔融料通過噴嘴注射到模具的型腔中,型腔中

96、的熔料經(jīng)過保壓、冷卻、固化定型后,模具在合模機構(gòu)的作用下,開啟模具,并通過頂出裝置把定型好的制品從模具頂出落下。</p><p>  按合模部件與注射部件配置的型式有臥式、立式、角式三種</p><p> ?。?)臥式注塑機:臥式注塑機是最常用的類型。其特點是注射總成的中心線與合??偝傻闹行木€同心或一致,并平行于安裝地面。它的優(yōu)點是重心低、工作平穩(wěn)、模具安裝、操作及維修均較方便,模具開檔大

97、,占用空間高度?。坏嫉孛娣e大,大、中、小型機均有廣泛應(yīng)用。</p><p> ?。?)立式注塑機:其特點是合模裝置與注射裝置的軸線呈一線排列而且與地面垂直。具有占地面積小,模具裝拆方便,嵌件安裝容易,自料斗落入物料能較均勻地進行塑化,易實現(xiàn)自動化及多臺機自動線管理等優(yōu)點。缺點是頂出制品不易自動脫落,常需人工或其它方法取出,不易實現(xiàn)全自動化操作和大型制品注射;機身高,加料、維修不便。</p><

98、;p> ?。?)角式注塑機:注射裝置和合模裝置的軸線互成垂直排列。根據(jù)注射總成中心線與安裝基面的相對位置有臥立式、立臥式、平臥式之分:①臥立式,注射總成線與基面平行,而合??偝芍行木€與基面垂直;②立臥式,注射總成中心線與基面垂直,而合模總成中心線與基面平行。角式注射機的優(yōu)點是兼?zhèn)溆信P式與立式注射機的優(yōu)點,特別適用于開設(shè)側(cè)澆口非對稱幾何形狀制品的模具。</p><p>  目前,常見的注塑裝置有單缸形式和雙缸

99、形式,我廠注塑機都是雙缸形式的,并且都是通過液壓馬達直接驅(qū)動螺桿注塑。因不同的廠家、不同型號的機臺其組成也不完全相同,下面就對我廠用的機臺作具體分析。</p><p>  工作原理是:預(yù)塑時,在塑化部件中的螺桿通過液壓馬達驅(qū)動主軸旋轉(zhuǎn),主軸一端與螺桿鍵連接,另一端與液壓馬達鍵連接,螺桿旋轉(zhuǎn)時,物料塑化并將塑化好的熔料推到料筒前端的儲料室中,與此同時,螺桿在物料的反作用下后退,并通過推力軸承使推力座后退,通過螺母拉

溫馨提示

  • 1. 本站所有資源如無特殊說明,都需要本地電腦安裝OFFICE2007和PDF閱讀器。圖紙軟件為CAD,CAXA,PROE,UG,SolidWorks等.壓縮文件請下載最新的WinRAR軟件解壓。
  • 2. 本站的文檔不包含任何第三方提供的附件圖紙等,如果需要附件,請聯(lián)系上傳者。文件的所有權(quán)益歸上傳用戶所有。
  • 3. 本站RAR壓縮包中若帶圖紙,網(wǎng)頁內(nèi)容里面會有圖紙預(yù)覽,若沒有圖紙預(yù)覽就沒有圖紙。
  • 4. 未經(jīng)權(quán)益所有人同意不得將文件中的內(nèi)容挪作商業(yè)或盈利用途。
  • 5. 眾賞文庫僅提供信息存儲空間,僅對用戶上傳內(nèi)容的表現(xiàn)方式做保護處理,對用戶上傳分享的文檔內(nèi)容本身不做任何修改或編輯,并不能對任何下載內(nèi)容負(fù)責(zé)。
  • 6. 下載文件中如有侵權(quán)或不適當(dāng)內(nèi)容,請與我們聯(lián)系,我們立即糾正。
  • 7. 本站不保證下載資源的準(zhǔn)確性、安全性和完整性, 同時也不承擔(dān)用戶因使用這些下載資源對自己和他人造成任何形式的傷害或損失。

評論

0/150

提交評論