(S)科学化的注塑成型产品设计

1、科学化的科学化的注塑成型产品设计注塑成型产品设计徐昌煜徐昌煜2016年年4月月16日日上海众安电器塑料有限公司厚度设计厚度设计 产品设计中壁厚不均带来的麻烦比任何其它问题设计带来者都要严重。 这些麻烦包括了雾斑、 喷流痕、迟滞痕、 应力痕、气痕、 焦痕、 缩痕和缩孔、 短射、 熔接线、 翘曲变形以及周期时间长等。 这些麻烦都可用CAE以直接或间接的方式预测。 设计高收缩率的结晶性注塑成型品时，设计者应将壁厚变化限制在10%以內。 就低收缩率的非结晶性塑料而言， 许容壁厚变化可到25%。壁厚壁厚 Wall ThicknessWall Thickness Validation“Plastic an

2、d composite simulations shape the car light weight future” presented by Dr. Venny Yang(楊文遠), President of CoreTech System Co., Ltd. (Moldex3D), at Seminar of “How to improve productivity in plastic injection molding”, Bangkok, Thailand, July 9, 201411Filling pattern causes air trapOriginal design of

3、 3.0mm thick.Revised designProblem and Solution2.43.0(3.0-2.4)/3.0 = 20% 3 x (T- t)not recommendedrecommended转角设计转角设计 当一90转角的内圆角半径小于名义厚度的25%时，角落就会有高的应力集中。 内圆角的半径增加到名义厚度的75%时，二壁交会处就能进而强化。 可接受的平均内圆角半径是名义厚度的50%。转角半径转角半径 Corner Radius转角转角 CornerStress Concentration应力集中系数应力集中系数K的定义： 真实最大应力(不连续处的峰值)对预期的(典

4、型力学用于规范几何形状及净截面-忽略了较复杂的应力分布-上的公式决定的)应力的比例。Stress concentration (or intensity) factor, K, is defined as the ratio of the true maximum stress (the peak stress at the discontinuity) to the stress anticipated or determined using classical formulas of mechanics (for regular geometries) for the net sectio

5、n, ignoring the more complex stress distribution. 内圆角半径内圆角半径與應力集中與應力集中 Fillet Radius and Stress Concentration00.60.81.01.21.40.20.41.01.52.02.53.0R / tK123Rapplied loadtK：stress concentration factorR：fillet radiust ：wall thickness碎裂地磅零件, PA66, 开裂, Oct. 2008根部尖角地磅零件, PA66, 开裂, Oct. 2008在尖角部位倒圆R2.5mm，

6、开裂问题解决。用半径规(R规)测根部倒圆半径地磅零件, PA66, Oct. 2008根部倒圆在尖角部位倒圆R2.5mm，开裂问题解决。地磅零件, PA66, Oct. 2008From: TJTo: 徐老师 Sent: Thursday, April 30, 2015 3:40 PMSubject: 水管接头开裂问题 徐老师，您好： - 最近做了一个案例，是属于水管接头的产品开裂问题，我结合了Moldflow与NX Nastran做了个分析，如果老师有空的话，能否指导一下，希望继续向老师学习结构强度的知识。 - 谢谢老师！ 祝老师身体健康！ TJModel Overview The size

7、 of the water way for faucet and the main thickness are shown below:Model OverviewVariantPart info.Part size(mm)85*56*30Thickness(mm)1.93.2 PA6T/6I 在 2015-04-30 22:06:09，Charles Hsu 写道： T. J.：应力集中处有三：尖锐之转角； 2) 熔接线； 3) 缩孔。1) 之是否在计算应力时考虑，只要找一处转角如V2之E，将其R从1mm改成0.1mm，跑CAEs后，看该处应力是否有明显的增加即知。2)和3)之未能考虑应力集

8、中则是在预料之中。 让我知道1)项测试的结果，再说。 徐昌煜2015年4月30日于日本盛冈From: T. J.To: Charles Hsu Sent: Monday, May 4, 2015 7:56 PMSubject: Re:Re: 水管接头开裂问题分析报告！ 徐老师： 谢谢您的回复！ 我将E处圆角由R1.0mm改成R0.1mm后，应力急速升高，具体见附件。NX Nastran是考虑了尖角处的应力集中现象。Z. T. J.圆角比较圆角比较V2_R1.0mmV2_R0.1mmR1.0mmR0.1mm最大应力最大应力 (V2R1.0mm)此处最大应力：91MPa最大应力最大应力 (V2R0

9、.1mm)此处最大应力：250MPa脱模角设计脱模角设计脱模角脱模角 Draft Angles脱模角脱模角 Draft Angles脱模角太小，会导致顶白、拖白或周期时间长等缺陷。脱模角以不小于0.5为原则，而以大于1为宜。 当然，在客户可以接受的范围以内，脱模角是愈大愈好。脱模角脱模角 Draft Angles侧壁：1.5t(顶)1.6t(底) x 12h单边脱模角0.24ABS, 浙江省乐清市, 脱模不易, 2004. 3. 8.四型腔模开三腔方能顶出，环保故，不得加脱模剂。半边脱模角仅0.4酒瓶包装盒, PET, 四川省宜宾市, crack at 10mm from open end a

10、t ejection, 2003. 7. 16.As a general guideline, 1.5 min. per 0.025mm (0.001 inch) depth of texture needs to be allowed for in addition to the normal draft. For example, a heavier texture surface such as leather texture (with a depth of 0.125 mm/0.005 inch) requires a min. draft of 7.5. 當模面具皮紋時，以光滑模面

11、所須脫模角為基礎，皮紋深度每0.025mm，脫模角要增加1.5 。 比方說，皮紋深度是0.125mm時，脫模角要增加7.5。脱模角與皮紋脱模角與皮紋 Draft Angles and Texture加強筋加強筋(肋肋)、角板、螺柱设计、角板、螺柱设计Though all of the projections shown here are different, the design guidelines are the same for each of the shapes. 虽然所有的突出件并不相同， 但是设计导引却是类同的。ProjectionsWall Thickness, RibConv

12、entional0.080 to 0.125 in(2.0 to 3.2 mm)owallwallribmmrthtt21375. 046 . 0Thinwall:0.050 to 0.080 in 0.050 in(1.2 to 2.0 mm)( 1.2 mm)oowallwallwallwallribtmmrthttt121*6 . 0375. 046 . 0owallwallwallribtrthtt1*6 . 0*4Wall Thickness, GussetsConventional0.080 to 0.125 in(2.0 to 3.2 mm)owallwallgussetmmrt

13、htt21375. 046 . 0Thinwall:0.050 to 0.080 in 0.050 in(1.2 to 2.0 mm)( 1.2 mm)oowallwallwallwallgussettmmrthttt121*6 . 0375. 046 . 0owallwallwallgussettrthtt1*6 . 0*4Wall Thickness, BossesConventional0.080 to 0.125 in(2.0 to 3.2 mm)IDODmmrthttowallwallboss221375. 046 . 0Thinwall:0.050 to 0.080 in 0.05

14、0 in(1.2 to 2.0 mm)( 1.2 mm)IDODtmmrthtttoowallwallwallwallboss2121*6 . 0375. 046 . 0IDODtrthttowallwallwallboss21*6 . 0*4脱模角脱模角 Draft Angles突出件在和名义板壁交会处的建议厚度：以高收缩率的结晶性塑料而言，可采用名义壁厚的50%。 以低收缩率的非结晶性塑料而言，可采用名义壁厚的75%。The recommended thickness at the junction of a projection and the nominal wall (NW) is

15、50% of the NW thickness for high-mold-shrinkage, crystalline materials. The lower-mold-shrinkage-factor, amorphous plastics can have thicknesses of up to 75% of the parts NW thickness. 突出件壁厚突出件壁厚Thickness of the Projection缩痕缩痕 Sink MarkPA, 浙江省杭州市,缩痕, 2003. 4. 19.Both ribs and base plate are 1.5mm th

16、ick.PA, 浙江省杭州市, 缩痕, 2003. 4. 19.缩痕缩痕 Sink Mark从成型容易的观点来看，突出件的高度以产品名义壁厚的2.5到3倍为宜。From an ease of molding perspective, the height of projections should be limited to 2.5 to 3 times the part nominal wall thickness.突出件高度突出件高度Height of the Projection距离应大于产品名义壁厚的2倍。 使得模具钢材具备足够的强度以抵抗弯曲，并且提供足够的吸热区，以免产生缩痕和成型

17、应力。The distance between a projection and the parts vertical sidewall, or between closely spaced projections should be at least 2 times the parts nominal wall thickness, so the mold steel provide enough strength to resist bending and enough heat sink to avoid sink mark and molded-in stress.突出件和侧壁突出件和

18、侧壁/突出件的距离突出件的距离The Distance between Projection and Side Wall/Projection孔设计孔设计孔孔 Holes以注射成型而言，圆孔形状理想，原因是塑料冷却时，会收缩紧扎在型芯销上，若销为圆形，应力会均匀的分布在孔缘塑料表层中。孔孔 Holes这一尼龙风扇因安装孔的直线孔缘末端的锁入应力而损毁。This nylon fan failed due to molded-in stress at the end of the straight section on the mounting hole.- Glenn Beall, IMM, J

19、une 2001 -孔孔 HolesFailures at sharp corners were eliminated by outwardly extending radiuses in this part.- Glenn Beall, IMM, June 2001 -孔孔 Holes最初，此一玻纤补强的尼龙计时链轮中央的方型驱动轴孔，有四个锐角。 使用几个月后，这些链轮，从方孔的锐角，到其附近的链轮齿根，产生裂隙而报废。 后来，在方孔的四个角落，加了向外延伸的小孔之后，链轮便不再开裂。The glass-fiber-reinforced nylon timing sprockets wer

20、e introduced with sharp corners on the square drive shaft hole. These sprockets failed after several months in the field due to cracks radiating from a corner on the square hole to the root of a nearby gear tooth. These field failures were eliminated by adding the outwardly extending radiuses.孔孔 Hol

21、es孔A和B能以简单直接开模的方式成形，孔C则须要一较复杂的侧向运动型芯，方能成形。Holes A and B can be molded with a simple, straight opening mold. Hole C requires a more complex side-acting mold.- Glenn Beall, IMM, Aug. 2001 -从易于成型的观点来看，相邻二孔缘的距离，或是孔缘和产品边缘的距离，至少要有壁厚的两倍，而绝对不可小于壁厚。From an ease of molding perspective, the distance from one h

22、ole to the next , or to the edge of a part, must be at a minimum two times the parts wall thickness, and never less than the parts wall thickness.- Glenn Beall, IMM, Aug. 2001 -孔孔 Holes孔孔 Holes图中的孔太靠近产品的边缘，塑料的收缩使得该孔和其周围的薄壁都因之扭曲。The hole shown here is too close to the edge of the part. Shrinkage of t

23、he plastic material has distorted this hole and the thin wall around it,despite the fact that the distance between the hole and the edge of the part is 1.6 times the parts wall thickness.- Glenn Beall, IMM, Aug. 2001 -孔孔 Holes盲孔A的长径比应以2:1或3:1为限。 形成穿孔B的型芯销的自由端是顶在定模面上。 这样的型芯销获得支持，而长径比可增加到6:1。如图中的C所示，将

24、型心延伸至定模侧的配合孔，可以提供额外的支撑，两头支撑的型心销的长径比可达12:1。 如图中的D所示，以二支型心销成型深孔，可以消除型心销和定模面的磨耗。 这种方法产生的孔也可有12:1的长径比。- Glenn Beall, IMM, Oct. 2001 -结构设计结构设计选择弹性模量选择弹性模量(E)大的塑料大的塑料IEMr1rMMwherer : radius of the curvature of the beam 梁的曲率半径梁的曲率半径M : bending moment 弯曲力矩弯曲力矩E : modulus of elasticity 弹性模量弹性模量I : moment of

25、inertia 惯性矩惯性矩弹性模量弹性模量 EModulus of Elasticity, EStrainStressE 任一材料在弹性范围内，遵循虎克定律(Hookes Law)，即应力对应变的比值为一常数，此一常数称之为弹性模量，可以MPa量之。E or (E1, E2), GPaPP1.700ABS2.600PC2.800PA662.963PP-GF30(4.200, 2.500)PC-GF30(7.000, 4.500)PA66-GF30(7.012, 4.592)PA66-GF50(L/D=25)(16.000, 10.000)PA66-GF50(L/D=100) (16.560,

26、 9.680)Mg Alloy 45Composite*190Steel200(E1, E2)分别为塑料在流向和垂直流向的弹性模量。表中打*号者为韩国LOTTE Chemical于2014年11月5日在余姚宾馆举行的第十届中国塑料产业发展(国际)论坛的報告“Technology of Automobile Lightweight Material”上发表的碳纤增强复合材料的E值。(E1, E2) are the moduli of elasticity along the flow and across flow directions, respectively.弹性模量弹性模量E Modul

27、us of Elasticity, E增加制品的单位用料的增加制品的单位用料的惯性矩惯性矩(I)和极惯性矩和极惯性矩(J)IEMr1rMMwherer : radius of the curvature of the beam 梁的曲率半径梁的曲率半径M : bending moment 弯曲力矩弯曲力矩E : modulus of elasticity 弹性模量弹性模量I : moment of inertia 惯性矩惯性矩yxyzydASEC B-BwhereM : bending moment 弯曲力矩弯曲力矩I : moment of inertia of A with respect

28、 to z axis 惯性矩惯性矩A : cross-sectional area 截面积截面积 (截面线处截面线处)MBBdAyIA2yzyndASEC B-BWhereI : moment of inertia of A with respect to z axis 惯性矩惯性矩A : cross-sectional area 截面积截面积 nkkknnnnAAyAyAyAyAydAyI1221212221212A4A5A8A11AnAn-1A1A2y2y11y4or冰箱抽屉, PS, 增强、省料、避免缩痕冰箱抽屉, PS, 考虑强度和省料, 2011. 7. 9.z用料多，然而强度和刚度

29、仅略增。用料少，然而强度和刚度仅略减。SEC. A-AAA实心唇缘与带孔唇缘的比较实心唇缘与带孔唇缘的比较冰箱抽屉, PS, 考虑强度和省料, 2011. 7. 9.zz在同样强度和刚度下用料多而有缩痕之顾虑。在同样强度和刚度下用料少而无缩痕之顾虑。加强筋加强筋板与浪板之比较板与浪板之比较Where：柄一端固定，另一端承受转矩下，单位柄长旋转的的角度：柄一端固定，另一端承受转矩下旋转的的角度L：length of shaft柄长T : torque转(力)矩G：modulus of elasticity in shear (or shear modulus) 剪切弹性模量E : modulus

30、 of elasticity 弹性模量 ：Poissons ratio 泊松比J : polar moment of inertia of A with respect to z axis 极惯性矩：断面形心到dA形心的半径TLzdAFixed End固定端elongationaxialunitcontractiolateralunitEGdAA;)1(2J;GJTL2n32)(,sec)(32,sec) 3 . 4(444ioddJbartioncrossannularcircularhollowafordJbartioncrosscircularsolidaforGJTTorsion of

31、 a Circular Shaftdidod曾文水库观景楼, 2014. 3. 21.曾文水库是台湾最大的水库，位于嘉义县大埔乡与台南市楠西区交界的柳藤潭峡谷。AASEC. A-A二次气体穿透Secondary GasPenetration塑料注射Polymer Injection主要气体穿透Primary GasPenetration型腔部份短射Partial Shotin Cavity气体注射Gas Injection气体注射Gas Injection气体：大多采用氮气 Gas : Use Nitrogen, Mostly短射法短射法Short Shot Method气辅注射成型气辅注射成型Gas As