(S)科學(xué)化的注塑成型產(chǎn)品設(shè)計

1、科學(xué)化的科學(xué)化的注塑成型產(chǎn)品設(shè)計注塑成型產(chǎn)品設(shè)計徐昌煜徐昌煜2016年年4月月16日日上海眾安電器塑料有限公司厚度設(shè)計厚度設(shè)計 產(chǎn)品設(shè)計中壁厚不均帶來的麻煩比任何其它問題設(shè)計帶來者都要嚴重。 這些麻煩包括了霧斑、 噴流痕、遲滯痕、 應(yīng)力痕、氣痕、 焦痕、 縮痕和縮孔、 短射、 熔接線、 翹曲變形以及周期時間長等。 這些麻煩都可用CAE以直接或間接的方式預(yù)測。 設(shè)計高收縮率的結(jié)晶性注塑成型品時，設(shè)計者應(yīng)將壁厚變化限制在10%以內(nèi)。 就低收縮率的非結(jié)晶性塑料而言， 許容壁厚變化可到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轉(zhuǎn)角設(shè)計轉(zhuǎn)角設(shè)計 當(dāng)一90轉(zhuǎn)角的內(nèi)圓角半徑小于名義厚度的25%時，角落就會有高的應(yīng)力集中。 內(nèi)圓角的半徑增加到名義厚度的75%時，二壁交會處就能進而強化。 可接受的平均內(nèi)圓角半徑是名義厚度的50%。轉(zhuǎn)角半徑轉(zhuǎn)角半徑 Corner Radius轉(zhuǎn)角轉(zhuǎn)角 CornerStress Concentration應(yīng)力集中系數(shù)應(yīng)力集中系數(shù)K的定義： 真實最大應(yīng)力(不連續(xù)處的峰值)對預(yù)期的(典

4、型力學(xué)用于規(guī)范幾何形狀及凈截面-忽略了較復(fù)雜的應(yīng)力分布-上的公式?jīng)Q定的)應(yīng)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. 內(nèi)圓角半徑內(nèi)圓角半徑與應(yīng)力集中與應(yīng)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, 開裂, Oct. 2008根部尖角地磅零件, PA66, 開裂, Oct. 2008在尖角部位倒圓R2.5mm，

6、開裂問題解決。用半徑規(guī)(R規(guī))測根部倒圓半徑地磅零件, PA66, Oct. 2008根部倒圓在尖角部位倒圓R2.5mm，開裂問題解決。地磅零件, PA66, Oct. 2008From: TJTo: 徐老師 Sent: Thursday, April 30, 2015 3:40 PMSubject: 水管接頭開裂問題 徐老師，您好： - 最近做了一個案例，是屬于水管接頭的產(chǎn)品開裂問題，我結(jié)合了Moldflow與NX Nastran做了個分析，如果老師有空的話，能否指導(dǎo)一下，希望繼續(xù)向老師學(xué)習(xí)結(jié)構(gòu)強度的知識。 - 謝謝老師！ 祝老師身體健康！ 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 寫道： T. J.：應(yīng)力集中處有三：尖銳之轉(zhuǎn)角； 2) 熔接線； 3) 縮孔。1) 之是否在計算應(yīng)力時考慮，只要找一處轉(zhuǎn)角如V2之E，將其R從1mm改成0.1mm，跑CAEs后，看該處應(yīng)力是否有明顯的增加即知。2)和3)之未能考慮應(yīng)力集

8、中則是在預(yù)料之中。 讓我知道1)項測試的結(jié)果，再說。 徐昌煜2015年4月30日于日本盛岡From: T. J.To: Charles Hsu Sent: Monday, May 4, 2015 7:56 PMSubject: Re:Re: 水管接頭開裂問題分析報告！ 徐老師： 謝謝您的回復(fù)！ 我將E處圓角由R1.0mm改成R0.1mm后，應(yīng)力急速升高，具體見附件。NX Nastran是考慮了尖角處的應(yīng)力集中現(xiàn)象。Z. T. J.圓角比較圓角比較V2_R1.0mmV2_R0.1mmR1.0mmR0.1mm最大應(yīng)力最大應(yīng)力 (V2R1.0mm)此處最大應(yīng)力：91MPa最大應(yīng)力最大應(yīng)力 (V2R0

9、.1mm)此處最大應(yīng)力：250MPa脫模角設(shè)計脫模角設(shè)計脫模角脫模角 Draft Angles脫模角脫模角 Draft Angles脫模角太小，會導(dǎo)致頂白、拖白或周期時間長等缺陷。脫模角以不小于0.5為原則，而以大于1為宜。 當(dāng)然，在客戶可以接受的范圍以內(nèi)，脫模角是愈大愈好。脫模角脫模角 Draft Angles側(cè)壁：1.5t(頂)1.6t(底) x 12h單邊脫模角0.24ABS, 浙江省樂清市, 脫模不易, 2004. 3. 8.四型腔模開三腔方能頂出，環(huán)保故，不得加脫模劑。半邊脫模角僅0.4酒瓶包裝盒, PET, 四川省宜賓市, 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(dāng)模面具皮紋時，以光滑模面

11、所須脫模角為基礎(chǔ)，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。脫模角與皮紋脫模角與皮紋 Draft Angles and Texture加強筋加強筋(肋肋)、角板、螺柱設(shè)計、角板、螺柱設(shè)計Though all of the projections shown here are different, the design guidelines are the same for each of the shapes. 雖然所有的突出件并不相同， 但是設(shè)計導(dǎo)引卻是類同的。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脫模角脫模角 Draft Angles突出件在和名義板壁交會處的建議厚度：以高收縮率的結(jié)晶性塑料而言，可采用名義壁厚的50%。 以低收縮率的非結(jié)晶性塑料而言，可采用名義壁厚的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縮痕縮痕 Sink MarkPA, 浙江省杭州市,縮痕, 2003. 4. 19.Both ribs and base plate are 1.5mm th

16、ick.PA, 浙江省杭州市, 縮痕, 2003. 4. 19.縮痕縮痕 Sink Mark從成型容易的觀點來看，突出件的高度以產(chǎn)品名義壁厚的2.5到3倍為宜。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距離應(yīng)大于產(chǎn)品名義壁厚的2倍。 使得模具鋼材具備足夠的強度以抵抗彎曲，并且提供足夠的吸熱區(qū)，以免產(chǎn)生縮痕和成型

17、應(yīng)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.突出件和側(cè)壁突出件和

18、側(cè)壁/突出件的距離突出件的距離The Distance between Projection and Side Wall/Projection孔設(shè)計孔設(shè)計孔孔 Holes以注射成型而言，圓孔形狀理想，原因是塑料冷卻時，會收縮緊扎在型芯銷上，若銷為圓形，應(yīng)力會均勻的分布在孔緣塑料表層中?？卓?Holes這一尼龍風(fēng)扇因安裝孔的直線孔緣末端的鎖入應(yīng)力而損毀。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，此一玻纖補強的尼龍計時鏈輪中央的方型驅(qū)動軸孔，有四個銳角。 使用幾個月后，這些鏈輪，從方孔的銳角，到其附近的鏈輪齒根，產(chǎn)生裂隙而報廢。 后來，在方孔的四個角落，加了向外延伸的小孔之后，鏈輪便不再開裂。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能以簡單直接開模的方式成形，孔C則須要一較復(fù)雜的側(cè)向運動型芯，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 -從易于成型的觀點來看，相鄰二孔緣的距離，或是孔緣和產(chǎn)品邊緣的距離，至少要有壁厚的兩倍，而絕對不可小于壁厚。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圖中的孔太靠近產(chǎn)品的邊緣，塑料的收縮使得該孔和其周圍的薄壁都因之扭曲。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的長徑比應(yīng)以2:1或3:1為限。 形成穿孔B的型芯銷的自由端是頂在定模面上。 這樣的型芯銷獲得支持，而長徑比可增加到6:1。如圖中的C所示，將

24、型心延伸至定模側(cè)的配合孔，可以提供額外的支撐，兩頭支撐的型心銷的長徑比可達12:1。 如圖中的D所示，以二支型心銷成型深孔，可以消除型心銷和定模面的磨耗。 這種方法產(chǎn)生的孔也可有12:1的長徑比。- Glenn Beall, IMM, Oct. 2001 -結(jié)構(gòu)設(shè)計結(jié)構(gòu)設(shè)計選擇彈性模量選擇彈性模量(E)大的塑料大的塑料IEMr1rMMwherer : radius of the curvature of the beam 梁的曲率半徑梁的曲率半徑M : bending moment 彎曲力矩彎曲力矩E : modulus of elasticity 彈性模量彈性模量I : moment of

25、inertia 慣性矩慣性矩彈性模量彈性模量 EModulus of Elasticity, EStrainStressE 任一材料在彈性范圍內(nèi)，遵循虎克定律(Hookes Law)，即應(yīng)力對應(yīng)變的比值為一常數(shù)，此一常數(shù)稱之為彈性模量，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)分別為塑料在流向和垂直流向的彈性模量。表中打*號者為韓國LOTTE Chemical于2014年11月5日在余姚賓館舉行的第十屆中國塑料產(chǎn)業(yè)發(fā)展(國際)論壇的報告“Technology of Automobile Lightweight Material”上發(fā)表的碳纖增強復(fù)合材料的E值。(E1, E2) are the moduli of elasticity along the flow and across flow directions, respectively.彈性模量彈性模量E Modul

27、us of Elasticity, E增加制品的單位用料的增加制品的單位用料的慣性矩慣性矩(I)和極慣性矩和極慣性矩(J)IEMr1rMMwherer : radius of the curvature of the beam 梁的曲率半徑梁的曲率半徑M : bending moment 彎曲力矩彎曲力矩E : modulus of elasticity 彈性模量彈性模量I : moment of inertia 慣性矩慣性矩yxyzydASEC B-BwhereM : bending moment 彎曲力矩彎曲力矩I : moment of inertia of A with respect

28、 to z axis 慣性矩慣性矩A : cross-sectional area 截面積截面積 (截面線處截面線處)MBBdAyIA2yzyndASEC B-BWhereI : moment of inertia of A with respect to z axis 慣性矩慣性矩A : cross-sectional area 截面積截面積 nkkknnnnAAyAyAyAyAydAyI1221212221212A4A5A8A11AnAn-1A1A2y2y11y4or冰箱抽屜, PS, 增強、省料、避免縮痕冰箱抽屜, PS, 考慮強度和省料, 2011. 7. 9.z用料多，然而強度和剛度

29、僅略增。用料少，然而強度和剛度僅略減。SEC. A-AAA實心唇緣與帶孔唇緣的比較實心唇緣與帶孔唇緣的比較冰箱抽屜, PS, 考慮強度和省料, 2011. 7. 9.zz在同樣強度和剛度下用料多而有縮痕之顧慮。在同樣強度和剛度下用料少而無縮痕之顧慮。加強筋加強筋板與浪板之比較板與浪板之比較Where：柄一端固定，另一端承受轉(zhuǎn)矩下，單位柄長旋轉(zhuǎn)的的角度：柄一端固定，另一端承受轉(zhuǎn)矩下旋轉(zhuǎn)的的角度L：length of shaft柄長T : torque轉(zhuǎn)(力)矩G：modulus of elasticity in shear (or shear modulus) 剪切彈性模量E : modulus

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

31、 a Circular Shaftdidod曾文水庫觀景樓, 2014. 3. 21.曾文水庫是臺灣最大的水庫，位于嘉義縣大埔鄉(xiāng)與臺南市楠西區(qū)交界的柳藤潭峽谷。AASEC. A-A二次氣體穿透Secondary GasPenetration塑料注射Polymer Injection主要氣體穿透Primary GasPenetration型腔部份短射Partial Shotin Cavity氣體注射Gas Injection氣體注射Gas Injection氣體：大多采用氮氣 Gas : Use Nitrogen, Mostly短射法短射法Short Shot Method氣輔注射成型氣輔注射成型Gas As