電動機端蓋模具設計【壓鑄模具】【說明書+CAD】

電動機端蓋模具設計【壓鑄模具】【說明書+CAD】,壓鑄模具,說明書+CAD,電動機端蓋模具設計【壓鑄模具】【說明書+CAD】,電動機,模具設計,壓鑄,模具,說明書,仿單,cad CHrNESE JOURNAL OF MECHANICAL ENGINEElUNG 、，ol-23，No5，2010 。547 DOI：103901CJME201005547，available online at wwwcjmenetcorn；wwwcjmenetcomcn Design and Verification of an Auxiliary System for High Vacuum Die Casting GE Xiaohon912一，HUANG Hongwul，LI Hui2，and LIU Yadanl 1 School ofPhysics and MechanwalElectrical Engineering,Xiamen University,Xiamen 361005China 2 Institute ofMaterial Processing and DieMould Integrated Technology,Xiamen University ofTechnology, Xiamen 36102幺China Received January26，2010；revisedAugustl8，2010；acceptedAugust25，2010；published electronicallyAugust26，2010 Abstract：Vacuum die casting is the optimal method to produce high quality aluminum alloy componentsAt present，there arc still very few systematic studies on Vacllum die casting theory and equipment designOn the basis of the existing theories of the vacuum die casting pumping and venting systemsa simplified model is established in this researchThe model has an aggregate unit consisted of vacuum pump+buffer tank”and a cylindrical container(including the shot sleeve，cavity and exhaust channel)The theoretical analysis is carried out between the cavity pressure and the pumping time under different volume modelsAn auxiliary system for high vacuunl die casting is designed based on the above analysisThis system is composed of a vacuum control machine and a new vacuum stop valveThe machine has a human-computer control mode with“programmable logic controller(PLC)+touch SClealand a real-time monitoring function of vacuunl degree for buffer tank and die cavityThe vacuum stop valve with the“compressed gas+ piston rod+labyrinth groove”structure can realize the function of whole-process vacuum ventingThe henri,system shows great advantages on vacuuming the cavity with a much faster speed by making tests oil all existing die casting mold and a 250 t die casting machineA die cavity pressure less than 10 kPa can be reached within 08 s in the experiment and the porosity ofcastings can be greatly decreasedThe systematic studies on vacuum die casting theory and equipment have a great guiding significance for high vacuuin die casting，and call also be applied to other high vacuum forming in related theoretical and practical research Key words：vacuum die casting，pumping model，high vacuum,vacIllmll stop valve，auxiliary system 1 Introduction Higll vacuum die casting technology is a special die casting process during which a cavity pressure less than 10 kPa call be obtainedThis technology can reduce or eliminate the porosity in die castings，with the air entrainment content being merely 1-3 mL per 1 00 gThe obtained castings can be used for further processing such as heat treatment and welding。etctl-21The key technology of lligh vacuunl die casting is to design a highsensitive vacuum pumping systemThe difficulty lies in establishing a modeling of pumping processSome scholars have studied on the theoretical model or practical application in this aspect BAR-M匝IlL et alt3-41studied the air venting of die casting and the ph)rsical modeling of vacuunl pumping processThey believed there was a critical vent area during the die casting processWhca the effective vent area of a vent valve was smaller than the critical area，the venting process was insufficienthence a lot of gases were involved in the liquid metalWhen the effective vent area was larger, the liquid metal was overflowed easilyNOURIBORUJE一 Corresponding authorEmail：xmlggxh163corn This project is supported by Fujian Provincial Natural Science Foundation of China(Grant No2007J0 1 70)，and Xiamen Municipal Natural Science Foundation ofChina(Grant No3502220093034) RDIet alt51built a transient model for the residual air mass in the die cavity during the injection processThev considered the influence of the molten metal viscosity temperature，injection velocity and friction factor，and thus improved the numerical simulation calculation method in this fieldHERNANDEZet al【improved the model of BARM【EIR et a1and took into account such unsteady factors as friction and air flow variation during vacuum pumping1nhis improved physical model was suitable for both conventional die casting and vacuum die casting There were many other studies on the die casting venting and vacuum die casting pumping internationally，but most of them stayed at the theoretical level and were mostly numerical simulations for the venting process HUet al【卜of Tsinghua University，China，carried out the theoretical calculation and experimental study of the decline of vacuum pressure in the cavity pumped directly by a vacuunl pumpThey compared a theoretical curve with a measured curve of the pressure in the cavityOnly when the time of vacuum pumping exceeded 25 san ideal cavity vacuum pressure less than l 0 kPa could be obtailled 、)liA Net alL。厶刈from Huazhong University of Science and Technology,China，independently developed a key technology related to high vacuum die casting based on minimum filling time(MFT)methodThey designed an auxiliary system with a bufrer tank that the mechanical 萬方數(shù)據(jù) 548 GE Xiaohong,et al：Design and Verification ofan Auxiliary System for High Vacuum Die Casting valve could be closed by the impact of liquid metal flow This system could decrease the pressllre of cavity to 10 kPa within 1 s Based on the current Iiterature，few studies provide theoretically sound analysis and practical sound design for a vacuum die casting system with a buffer tankThis paper is to carry out theoretical research and calculation analysis of the high vacuum pumping system model with a buffer tank，to study the relationship between pressure in die cavity and the pumping time，and to develop a high vacuum die casting auxiliary system which Call satisfythe high vacuunl experiment requirements 2 Theoretical Model of Pumping System with a Buffer Tank The vacuum pumping scheme with a buffer tank is shown in Fig1【4】A large buffer tank，as a vacuum source， is added to extract the gas out of the cavity between the vacuum pump and the mouldThe gas in the buffer tank is drawn out unceasingly by the vacuum pump Fig1Scheme ofvacuum pumpkng system with a buffer tank A simplified model is given in Fig2 for the theoretical calculation of hi【曲vacuum venting based on the above scheme必n is the Math number at duct entrance，Jjlt is the Mach number at duct exit，and re(t)is the number of moles of gas in die cavity vacutlrtl entrance Fig2Theoretical calculation model for air venting In this model。the unfilled shot sleeve。the runner and the die cavity are combined and regarded as a cylindrical container fcalled the cylinder)【jJGases are vented through the duct to the buffer tank功e main resistance to gas flow is in the ductThe following assumptions about this model are made for the theoretical calculation： (1)AU gases are ideal gases (2)1nhe venting period is very short，the gases temperatu- re is at 300 k and the heat transfer of gases is not considered (3)111e effect of gases leakage on the venting process is neglected (4)The volume of vacuum valve duct is sinail compared to the gas duct，thus can be negligible According to the model established for the venting process in high vacuum die casting，the following formulas can be established to relate the gas pressure in the cavity to the pumping timeIn performing the calculations，and 朋rout at the duct entrance and exit can be obtained by solving Eqs(1)一(3)3一10l as follows： 警=愕L一陪1， m 篇P=(+盟2 M二廠老。(f) I ”J M。 ，+等M二 +竿帆2 t+l II (2) (3) Within the time interval At，the gases mass Am flowing from the cylinder through the vent to the outside can be obtained by Eq(4)t5-6： Am=pgAAt=PoM,(-bi+等M：產觸 The cavity pressures po(t)and p“力can be obtained by Eqs(5)，(6)，respectively： (5) (6) where the dimensionless quantity 4fLD is the resistance coefficient in the duct，usually taking 3 to 7p“f)is the pressure at duct exit，po(t)is the pressure in die cavity,k is the specific heat ratio of air,Am is the number of moles of gas entering the duct in unit timeP is the air density,R is the molar gas constant“is the gas velocity at the vent entrance，A=n(D2)2 is the vent cross-sectional are41，K is the cylinder volume，瑪is the buffer tank volume，and K is the duct volume，V4=“+ The gas duct has diameter of 20 mill and length of 3 m The buffer tank is selected with l 50 LThe vacuum pump with the pumping speed of 8 Ls is to be used，and the bufrer tank is pumped to have an initial pressure of 08 kPa r r一 豎 堅守半 一 一 m一 陋 II =、，、J f f，L，L 風 風 萬方數(shù)據(jù) CHINESE JOURNAL OF MECHANICAL ENGEERING 549 Table presents the values for the calculation TableValues for the initial calculation conditions Initial condition Value Cylinder volume VIL dllct Di8n柵Dmm Length Lm Pressure at 0 spo(O)kPa Pressure in final po(t)kPa Pressure at 0 sp，(O)kPa Specific heat ratio ofairK Resistance coefficient 4fLIrt o5，10，15 20 4 1013 lO 8 141 In the range of37here taking the value of5 Vacuum tank volume圪L 150 Duct volume nL 94 Pumping speed of the vacuulll pump 。 S(L5-1) 6 Molar gas constant R 83 I 4 Ambient temperature rK 300 Cylinder(shot sleeverunner and die cavity)with the volumes of 05 L10 L and 15 L are taken for the calculationne calculation results are as shown in Fig3 Whell=15 L，it only takes 073 s to decrease the pressure in the die cavity to 9885 kPa by pumping and the lowest pressure can reach 8974 kPataking only 083 s jd 瓷 善 躥 蘭 營 竺 凸 Fig3Relation curves between the die cavity pressure and time The calculation equations for the above theoretical model are established without considering the unceasing evacuation of the vacuum tank by the vacuum pumpThe time of pumping the buffer tank call be estimated by Eqs (7)，(8)1l】： 一咕g營， v=巧+ (7) (8) where t is the pumping time，昂is the nominal pumping speed,V is the volume of the target container,n is the volume of the buffer tank,坎is the volume of the pumping duct，pi is the initial pressure in the target container,P is the target pressure in the target container, and the dimensionless quantity K is the correction cocfficient， taking l herein】 111e time to pump the buffer tank to 08 kPa in advance is calculated as follows： ，=23量，q喜gP歹l一。一，、-，、150i+94。x lg10000063 s (9)l口一R V-9 8 000 、7 There is a relatively long time not necessarily to be of vacuum before the liquid metal filling the cavityThis time can be used to preevacuate the vacuum tank 3 Design and Realization of a High Vacuum Auxiliary System On the basis of the above theoretical modela high vacuum die casting auxiliary system is designed with following core parts such as the control systemvaounl valve and pneumatic systemThe design and realization processes will be introduced briefly in the following sections 31 Design and realization of the control system The control system adopts the industrial control mode of “PLC+touch screen”It can perform realtime monitoring of the vacuum pump，various solenoid valves，buffer tank， vacuum valve and die cavityThe schematic diagram and photo of the control system are given in Fig4The operation interfaces are given in Fig5 32 Design of vacuum valve and pneumatic control To achieve the best vacuum die casting result，it must be guaranteed that high vacuum level in the die cavity can be maintained until the cavity is completely filled with liquid metalThe vacuum pumping charmel should be closed at the moment that the filling endsTherefore。the vacuum valve working mode is the key to realize this processThe developed vacuum valve has different structure from the existing onestl2-19A mode of“compressed gas+piston rod J1abyrinth grooveis originally created and the inertial impact of the liquid metal is used to close the vent channelwhose response time is only 15 msTherefore the wholeprocess vacuum ventingis realized in die casting Finally,the automatic reset of the vacuum valve is achieved with the assistance of the compressed gasThe structure and photos of the vacuum valve are given in Fig6The vacuum valve can also be controlled by the compressed air The circuit diagram of pneumatic control of vacuum valve isgiven inFig7 萬方數(shù)據(jù) 550 GE Xiaohong，et al：Design and Verification ofan Auxiliary System for High Vacuum Die Casting (a)Control system diagram I，2-Programmable controller；3-Touch screen； 4，5-Solenoid valve；6-Pressure transmitier； 7-Pressure regulating valve (b)Control system object Fig4Schematic diagram and object ofthe control system Fig5Operation interfaces ofthe control system (a)Inlemal structure ofthe vacuLim valre module Outside configuration andphoto ofthe vacuumvalve Fig6Structure and photos of the vacuum valve Fig7Circuit diagram ofthe pneumatic control ofthe vacuum valve 1，5-22 way pilot-operated solenoid valve； 2，632Way pilotoperated solenoid valve； 3-32way direct-operated solenoid valve； 4-22way directoperated solenoid valve； 7，8一Pressure regulating valve； 9一Pressure transmitter；10一Filter 4 Verification and Analysis of the Vacuum Pumping with the High Vacuum Auxiliary System 41 Experimental equipment and method ADCl2 alloy is used as the test material and the vacuum 萬方數(shù)據(jù) CHINESE JoURNAL OF MECHANICAL ENGNEERING 551 die casting mould is designed for an automobile part(a bar)， whose mass is 104 kg containing casting itself,the gating system and the ventAs shown in Fig8(a)，the developed vacuum valve and mould are installed on the die casting machine，F(xiàn)ig8(b)shows the bar produced by this system Fig8Experiment ofvacuum die casting A ccrtain amount of ADC 1 2 iS melted to 953 Krefined for 1 5 rain by blowing argonand stood still for 1 0 min for thermal insulation castingThe mould iS heated to a preheating temperature 523 K with all electric heating rod The vacuum pressure in the buffer tank iS set to 1 0 kPa The vacuum levels following time in the cavity are shown in Fig9One curve is obtained by theoretical calculation and the other by measuring in the experiment processne two curves have the salne trend in the pressure drop section 芒 暮 l 璺 魯 套 者 Pumping time ts Fig9Measurement and theoretical calculation resuk 42 Observation of porosity castings The fatal defect of aluminum alloy die castings iS the porosityBy sampling，the X-ray inspection of the bars in connecting part without heat treatment indicates that the porosity of castings produced by conventional die casting is 1 00And the gas holes are widely distributed，whereas barely any gas hole can be seen in the castings by high vacuum die castingThe typical distribution of the gas holes are as shown in Fig1 0Thewhole-process vacuunl of this system iS synchronized with the iniectionachieving the whole-process venting，and satisfying the requirement of low porosity to the greatest extent Fig10Xray pictures ofcastings produced by conventional and vacuum die casting 5 Conclusions (1)The cavity venting process with a buffer tank in high vacuum die casting iS calculated and analyzedOn the basis of the specific parameters selected for the developed high Vacuum die casting auxiliary systemthe theoretical curves of cavity venting with different volumes are plotted ResulB show that，for aluminum castings less than 4 kg，the cavity pressure Can be decreased to l 0 kPa within 08 S theoretically using the vacuum pumping with a buffer tank of 1 50 LTo a certain degreeit reflects the vacuum pressure variation仃end in the cavity (2)A high vacuum die casting auxiliary system is developed based on the above calculation and analysis This system has a touch control interface with advantages of the simplicity and fast responseand a mechanical 萬方數(shù)據(jù) 。552。 一鯉Xiaohong,et al：Design and Verification ofan Auxiliary System for High Vacuum Die Casting vaL：Illlnl valve that call achieve vacuunl venting during the whole process with the response time of only 15 ms (3)The higIl vacuunl die casting auxiliary system has been used for trial production of ADCl2 alloy barsThe porosity decreases significantly compared to the conventional die casting technique (4)The systematic studies on vacuunl die casting theory and equipment have a great guiding significance for high vacutlnl die casting，and can also be applied to other hiigh vacuum forming such as vacuulTl injection References 【l】ZHAO Yunyun，WAN Li，PAN Huan，et a1Design and application of the vo,ctlllll,!shut-off valve and vacullln system for high vacuulll die castingCThe 12th National Special CastingNonferrous Alloys Annual Conference,Fuzhou,China,July 263 12008： 451454(in Chinese、 【2】ZHAO Ytmyun,WAN Li，PAN Huan，et a1Development and application of high vacuum die casting in aluminum alloyJ Special CastingNonferrous Alloys，2008，28(11)：858-861(in Chinese) 【3】BAR-MEIR G，ECKERT E R G，GOLDSTEIN R JAir venting in pressure die castingJFluids Eng，1997，1 19(2)：473_476 【4】BAR-MEIR G，ECKERT E R G，GOLDSTEIN R JA model of vacumpumpingJ爿m紀Z ManufScfEng，1996，118(2)：259- 265 【5】NOURI-BORUJERDI A，GOLDAK J AModeling of air venting in pressure die casting processJASMEManuf SciEng，2004， 12“3)：577-581 【6】HERNANDEZ JLOPEZ JFAURA FInfluence of unsteady effects on air venting in pressure die castingJASME Trans，2001， 1 23(4)：884-892 【7】HU Bo，ONG Shoumei，MASAYAKI M，et a1Calculation aad experiment oll cavity vacuum p托ssurc in vBom die casting processJChina Foundry，2007，56(3)：258-261 【8】HU 13,o，oNG Shoumei，MASAYAKI M，et a1Comparison experiments on evacuating capability of a high vacum valve and a zig-zag valve in vacBunl die casting process叨China Foundry, 2006，55(4)：355-359 【9】WAN Li，PAN Huan，LUO JirongApplication and development trends ofhiigh vacuull die casting process and die casting aluminum alloys with high strength and ductilityJSpecial Casting Nonferrous Alloys，2007，27(12)：939_942(in Chinese) 【i0WANG L HMathematical modelling of air evacuation in die casting proc6絡$via CASTvac and other venting devicesJ International Journal of Cast Metals Research，2007，20(4)： 19l197 【1l】DAO DaanVacuum desgn manuaMBeijing：National Defense 【12】 【13l 【14】 【15】 【16】 【17 【l 8】 【19】 Industry Press2004(in Chinese) IWAMOTO TermyuZI NinngyokuVacuum control equipment and VacBLIm die casting method of die casting machine：China-CN 1709613【P】20051221 KAToU KoumeiMethod to eontroI the vacllunl level in vaGuunl die casting and vacuum control to accomplish this mahod：China, CN 115092lfPI1994一_0604 L1 YufengDie casting die designed and made by Japan-die casting method+local pressure pinJEn舒ne Fuel System，2000，12(4)： 2肚24 WISER JA valve device used in die casting venting：Chi眠CN 1095000P1994一l l16 HODLER FDie casting 1095653P1994-1 1-30 LI Q BVacuum valve 25 1 8623P200210-30 module with rant valve：China,CN of die casting machine：Chin亂CN GU Y W，L1 J XVacuum valve sllaletttre of a die casting machine： China,CN 2301318P11998-12-23 ZHAO Y Y，WAN L，PAN HVacuum stop valve used for high vacuum die casting：China,CN 201061824P2008-05-21 Biographical notes GE Xiaohong。bom in 1964is currently a Phi)candidate in School of Physics and MechanicalInstitute of Material Processing and Die ECKERT E R G;GOLDSTEIN R J Air venting in pressure die casting外文期刊 1997(02) 2.ZHAO Yunyun;WAN Li;PAN Huan Development and application of high vacuum die casting in aluminum alloy期刊論文-Special Casting PAN Huan;LUO Jirong Application and development trends of high vacuum die casting process and die casting aluminum alloys with high strength and ductility期刊論文-Special Casting XIONG Shoumei;MASAYAKI M Comparison experiments on evacuating capability of a high vacuum valve and a zig-zag valve in vacuum die casting process期刊論文-China Foundry 2006(04) 5.HU Bo;XIONG Shoumei;MASAYAKI M Calculation and experiment on cavity vacuum pressure in vacuum die casting process期刊論文-China Foundry 2007(03) 6.HERNANDEZ J;LOPEZ J;FAURA F Influence of unsteady effects on air venting in pressure die casting 外文期刊 2001(04) 7.NOURI-BORUJERDI A;GOLDAK J A Modeling of air venting in pressure die casting process外文期刊 2004(03) 8.BAR-MEIR G;ECKERT E R G;GOLDSTEIN R J A model of vacuum pumping外文期刊 1996(02) 9.ZHAO Yunyun;WAN Li;PAN Huan Design and application of the vacuum shut-off valve and vacuum system for high vacuum die casting 2008 10.ZHAO Y Y;WAN L;PAN H Vacuum stop valve used for high vacuum die casting 2008 11.GU Y W;LI J X Vacuu