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注塑工艺设计-培训资料.pdf
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1、注塑工艺设计注射成型周期Injection Molding Cycle4(1).充填阶段Filling st age(2).后充填阶段Post-filling st age(3).开模阶段Mold-opening st age1.成型周期开始Cycle begins2.充填/保压切换点F/P swit ches over3.型腔完全充满Cavit y is all filled4.保压释放Packing pres.is released5.冷却/开模切换点P/0 swit ches over6.开模Mold opens7.关模及下个周期开始Mold closes and next cycle
2、begins模温 Mold TemperatureMold t emperat ures are import ant in det ermining final part finish and molded-in st ress levels.Cold molds are more difficult t o fill,necessit at ing high inject ion pressure and melt t emperat ure.Heat ed molds generally produce a part wit h a bet t er finish and lower m
3、olded in st ress.Because of t he high heat dist ort ion t emperat ures of engineering t hermoplast ic resins,part s are eject ed easily at higher t emperat ures.The midpoint of t he suggest ed range w川 generally give good result s wit h respect t o part appearance and cycle t ime.Higher mold t emper
4、at ures can result in bet t er flow,st ronger knit lines and lower molded-in st resses.Using lower t han t he suggest ed mold t emperat ures will generally result in higher molded-in st resses and compromise(危及)part int egrit y.熔胶温度 Melt TemperatureAs a general rule,residence t ime should be as shor
5、t as possible when molding near t he maximum suggest ed melt t emperat ure.When processing near,or at,t he uppe门imit of t he melt range,t he shot weight should approach 80 t o 90%of t he cylinder capacit y of t he machine.(当料温接近上限时,射料量应当接近注射机射胶量 的80至)90%)If t he cylinder t emperat ure exceeds t he u
6、pper limit of t he suggest ed melt range,t hermal degradat ion of t he resin and loss of physical propert ies may result.熔胶温度 Melt TemperatureA relat ively small increase in screw speed(RPM)or back pressure can result in a dramat ic increase in melt t emperat ure wit h no change in cont roller set p
7、oint.(即使设定料温不变,稍微增加螺杆 转速或背压就会明显增加融胶温度。)It is suggest ed t hat melt t emperat ures be measured using hand-held pyromet ers.These measures should be t aken on t he t hermoplast ic melt s aft er t he machine is on cycle.Increased melt t emperat ures will reduce viscosit y and increase resin flow,t hus
8、providing for longer flow for t hin wall sect ions and help produce lower residual st ress.When higher melt t emperat ures are used,reduced barrel/residence t imes are needed t o minimize any degradat ion of t he resin.螺杆转速Screw SpeedScrew speeds(RPM)should be adjust ed t o permit screw rot at ion d
9、uring t he ent ire cooling cycle wit hout delaying t he overall cycle.Low screw speeds w川 help reduce glass fiber damage during plast icat ion when molding reinforced grades.(塑化力口中甫弓货物塑料 日寺,低的螺捍醇速可以减少玻,幽的揖毁。)Suggest ed screw speed is dependent on screw diamet er.Opt imum linear velocit y of screw O.
10、D.is t ypically 8 inches(202.4 mm)per second.RPM=(60 x 8 inches/second or 202.4mm/second)/(ttx screw diamet er).For example,for a 3 inch(75.9 mm)diamet er screw:3(screw Dia.)x 3.1416=9.4248 divided int o 8 inches(202.4 mm)per second(opt imum linear velocit y)x 60=51 RPM.背压 Back PressureBack Pressure
11、A back pressure of 50 t o 100 psi(0.35 t o 0.7 MPa)is suggest ed t o help ensure a homogeneous melt and maint ain consist ent shot size.(推荐采用0.35到0.7 MPa的 背压,以确保均匀的融胶及维持一致的射料量)Higher back pressures used t o improve melt mixing result in higher melt t emperat ures and possibly degradat ion due t o ex
12、cessive shearing of t he resin.射速 Injection SpeedThe fast est fill speed possible provides longer flow,fills t hinner wall sect ions,and helps t o creat e a bet t er surface finish.Slower fill is suggest ed for sprue-gat ed and edgegat ed part s t o help prevent gat e blush,splay and jet t ing.In t
13、hick wall part s 0.2 inches(5.06 mm)and up slow fill helps reduce sinks and voids.射压 Injection PressureInjection PressureThe act ual inject ion pressure will depend on variables such as melt t emperat ure,mold t emperat ure,part geomet ry,wall t hickness,flow lengt h,and ot her mold and equipment co
14、nsiderat ions.Generally,the lowest pressures which provide t he desired propert ies,appearance,and molding cycle are preferred.(一般来,最低射屋可以提供需求的性、外瞿免和成型遇期。)Ideally,inject ion pressure should vary t o maint ain t he int ended ram speed.This is called velocit y cont rolled inject ion and provides t he
15、molder a much more robust and respect able process t han cont rolling inject ion pressure during fill.射压时充填时间变化曲线Injection Pressure vs Fill TimeMat erial:ABS50,0 _45.0U-SHAPE Curves Bi40.035.030.00.005.0。5.FILL TIME(SEC)DVD盒的翘曲及锁模力需求Warpage and Required Clamp Force of a DVD BoxDV D盒,PP,广东省珠海市,2002.8
16、.6.DV D盒,PP,2型腔模,注射时间:1.8秒 公称厚度1.3mm,钱链厚度0.18mm产品简介产品:DV D Box 材料:PP产品尺寸(展开):284x191x9.4mm 产品尺寸(合上):136x191x14mm 模具为一出二。产品壁厚分布如上图所示,公称壁厚为1.3mm,侧壁壁厚为1.8mm、1.6mm和0.8mm,中间钱链处最小厚度为0.18mm。2方案比较表保压切换位置为99%,保压压力为切换时注射压力的80%.模温设定:8;料温设定:2601234567891011注射时间(S)1.50.20.50.81.01.21.51.82.02.53.0射压(MPA)49.956.1
17、46.844.644.143.844.145.546.14951锁模力(Ton)252191153158163168181194203221287*第1项没有采用优化的螺杆注射曲线,和使用优化曲线者(第7项)比,射压高出了 13%以及锁模力多出了39%。*第2项至第11项采用优化的螺杆注射曲线。U型曲线(注射压力vs注射时间)0 5 0 56 5 5 4(pdw)S置壬羔射出屋力V S射出畤DV D 盒(PP)模温设定:8;料温设定:260C对应最小 射压的注 射时间为 1.2秒。0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50f(S)U型曲线(锁模力vs注射时间)对应最小 锁
18、模力的 注射时间 为0.6秒。螺杆速率Ram SpeedProgrammed inject ion is suggest ed for part s wit h small gat es(pin gat es and subgat es).A slow inject ion rat e can be used at t he st art t o help eliminat e gat e blush,jet t ing,and burning of t he mat erial.Once underway,speed can be increased t o fill t he part.M
19、aint ain const ant melt front velocit y,and slow near end of fill t o opt imize part qualit y.螺杆速度时行程曲线Ram Speed ProfileI m IrIEec4:iori Control2felt temper mtre丽1 5。MHoko 21=x-200):99 85一 309 91 CINI r100Hoe speed ooritrol|re:IJ sp-dM mx 1 OO)*1I4-1 oo螺杆速度又寸行程设定的影响等速推进调整后的螺杆速度对行程设定较高的注射压力较低的注射压力MFV
20、&MFA的定义熔胶前沿速度Melt-Front Velocity(MFV)熔胶前沿截面积Melt-Front Area(MFA)前沿速度Melt Front Velocity前沿速度 在入子两 侧加快Melt front velocit y increases around t he insertt ime=t1 t ime=t2MFV的调整由于大部分的模具几何外型都相当复杂,固 定的螺杆速度不太可能提供固定的熔胶前沿推进 速度。每当型腔的截面积改变时,该区域的充填 速度就可能比其他区域充填的还要快,上图中表 示的,就是在一定的入口速度下,熔胶前沿推进 速度在入子的两侧突然加快的情形。这将会造
21、成 在上图中入子的两侧产生高剪切应力,可能会导 致成品的翘曲变形。螺杆速度对行程设定等速推进 调整后的螺杆行程设定pd s E B B|St roke%|熔胶通过浇口 熔胶填满型腔笔记本计算机LCD后盖LCD Cover,NotebookScale(10 mm)11优化的螺杆速度对行程曲线Optimized Ram Speed Profile(LCD Cover,Notebook)Filling:Recommended ram-speed vs.St roke100.0 C:C-MOLD_UserCI0417-100-30X100-30M00-3090.0(*)p 38dslEEP8PU3EE
22、038QZ6050.o o.430200.012.5 25.0 37.550.0 62.575.087.5100.0o o So.8 7St roke(%)熔胶流动情况Fill time=1.435s熔胶前沿推进Fil timeLgST u Fil nms e;i/A oknw YL_ sh.588 _Fil time-0 90KH|T _ScajvB_1Fill time j浦oktfW 3 1 ;Fill rime3国 q+XTVoWHtM/*,V 党优化的螺杆速度对行程曲线Recommended ram speed profile(rel):%st roke%speed0.000021.
23、705210.000075.396520.000091.321430.0000100.000040.000093.646950.000094.163860.000088.422670.000085.049680.000079.232390.000096.2543100.000031.3536充填/保压切换点控制方式Fill/Pack Switch-Over PointF/P swit ch-over byF/P swit ch-over by percent volume(Default input)F/P swit ch-over by hydraulic pressure(Realit y
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