模具基础知识讲解(二)---浇注系统设计.ppt

1、模具设计的优先順序 Priorities of Mold Design,浇注系統设计 (Filling System Design) 排氣系统设计(Venting System Design) 冷卻系統设计 (Cooling System Design) 脫模系統设计 (Ejecting System Design),万学超 2007.8.1,浇注系统的优先順序 Priorities of Filling System Design,产品设计 (Part Design) 型腔设计 (Cavity Design) 浇口设计 (Gate Design) 流道设计 (Runner Design) 噴

2、嘴设计 (Nozzle Design),典型的浇注系統 Typical Filling System,壁厚不均是注塑成型中最大的麻烦制造者。 这对薄壁产品尤然。 这些麻烦包括了迟滯現象、短射、凹陷、发赤、噴流、翘曲及长冷卻时间等；目前都可用CAE以直接或间接的方式預測。 Non-uniform wall thickness is the biggest trouble maker in plastic injection molding. This is especially true to thin-wall part. The troubles, including hesitation,

3、 short shot, sink mark, blush, jetting, warpage and long cooling time etc., can be predicted, directly or indirectly, by using CAE.,壁厚不均Non-uniform Wall Thickness,壁厚设变 Wall Thickness Design,掏空掏空 (1) Coring Out Design (1),掏空设计 (2) Coring Out Design (2),氣泡或和凹陷的形成 Void or/and Sink Mark Forming,肋厚和內圆角半径

4、的影响 The Effect of Rib Thickness & Fillet Radius,肋的底部厚度 Bottom Thickness of Rib,肋的设计 (1 ) Rib Design ( 1 ),肋的设计 (2) Rib Design ( 2 ),肋的设计 (3) Rib Design ( 3 ),与側壁相连之凸辕 (热塑性塑料) Boss at Wall ( Thermoplastics ),远离側壁之凸辕 (热塑性塑料) Boss Away From Wall ( Thermoplastics ),外側凸辕 Outside Boss,Where 1/r : 梁的曲率 cur

5、vature of the beam M: 弯曲力矩 bending moment E : 弹性模数 modulus of elasticity I : 断面积对中立轴的惯性矩 moment of inertia of the cross- sectional area with respect to the neutral axis EI : 挠曲刚性 flexural rigidity,挠曲刚性Flexural Rigidity,A variety of molded-in interlocks can add stiffness to thin-wall housing designs.

6、,各种一体成型的內锁件 能增加薄辕的刚性。,结构设计是薄辕成型零件的基础。 Structural design is the base of thin-wall molding parts. 薄辕成型产品不仅仅是一趋势，而且也是降低成本和提高竞争力的有效途径。 Thin-wall molding part is not only a trend but also an effective way to achieve cost reduction and competitiveness increase.,结构设计和薄辕成型产品 Structural Design & Thin-wall Mo

7、lding Parts,熔胶波前推进 Melt-Front Advancement,充填模式,积封和熔接线 Filling Patterns, Air-Traps and Weld Lines Location,熔接线 Weld Lines,材料 Material : PC-GF50,原设计 Original,更改设计 Revised,更改浇口位置以重新定位熔接线 Weld Lines Can Be Relocated By Changing Gate Location,典型对头熔接线伸张強度保留值 Typical Butt Weld Tensile Strength Retention Va

8、lues,熔接线冷料井 Weld Slug Well,对头熔接线 Butt weld,熔接线冷料井 Weld slug well,积风 Air Traps,排气 Vent,每增加一個浇口，至少增加一条熔接线，同時增加一個浇口痕迹、增加流道的体积以及增加較多的积风。 Every time one gate is added, one weld line, at least, one gate mark, more runner volume and more air traps will be added. 在型腔能夠完滿充填的前提下，浇口数目是愈少愈好。 As long as the cavi

9、ty is able to be filled appropriately, gates are the less the better. 为了減少浇口数目，每一浇口应就塑流力所能及的流长/壁厚比之內，找出可以涵蓋最大产品面积的进浇位置。 In order to reduce the number of gates, each gate shall be located at where the melt is able to cover maximum part area based on the largest melt flow length/thickness ratio.,浇口数目

10、The Number of Gates,The melt fills the inside cavities before filling the outside cavities.,The runner system shows that warmer, low-viscosity material (yellow and red) follows the inside wall when the melt splits at an intersection.,Melt ” Flipper ”,导致平直产品的浇口设计 Gate Design for Flat Part,浇口设计(减少滯流效应

11、 Gate Design to Avoid Hesitation,浇口设计(避免凹陷和氣泡) Gate Design to Avoid Sink Mark & Void,使用重叠浇口以避免噴流 Avoid Jetting by Using Overlap Gate,正確的浇口位置以避免噴流 Avoid Jetting by Locating Gate Correctly,使用凸片浇口以避免噴流 Avoid Jetting by Using Tab Gate,使用适当的浇口形状以避免噴流 Avoid Jetting by Profiling Gate Properly,塑料(Polymer):

12、POM 進澆處(Polymer entrance)： 澆口厚(Gate thickness) 1.2mm，模穴厚(Cavity thickness) 3.2mm 問題 (Problem)： 噴流(Jetting),Poor Design Causing Jetting,气辅成型冰箱把手,多浇口设计 Multi-Gate Design,浇口种类 Gate Types,矩形边缘浇口设计 Rectangular Edge Gate Design,扇形浇口设计 Fan Gate Design,重叠式浇口设计 Overlap Gate Design,凸耳浇口设计 Tab Gate Design,针点浇口

13、设计 Pin Gate Design,潜伏式浇口设计 Subgate Design,剪切速率 Shear Rate,剪 切 應 力 shear Stress 黏 度 viscosity 剪 切 速 率 shear rate,剪切應力 Shear Stress,水力直径 Hydraulic Diameter,Where is the hydraulic diameter 水力直徑 A is the cross-sectional area of the flow 流路断面积 P is the wetted perimeter 湿周長,水力直徑 Hydraulic Diameter,在不同剖面形狀

14、，相同断面积下之变化 Various runner profiles, based on the same cross-sectional area,流道尺寸设计 (1) Runner Sizing (1),D: 流道直徑 ( mm ) runner diameter in mm W: 下游塑料重量 ( g ) downstream plastic weight L: 流道长度 ( mm ) runner length in mm,流道尺寸设计 (2) Runner Sizing (2),流道尺寸设计 (3) Runner Sizing (3),流道尺寸设计 (4) Runner Sizing (4),流道尺寸设计(A1) Runner Sizing (A1),G : 重量 weight S : 零件厚度 thickness D : 参考直徑 reference diameter,流道尺寸設計(A2) Runner Sizing (A2),G : 重量 weight S : 零件厚度 thickness D : 参考