模具设计技术1 DESIGN FOR MOLD ABILITY (共225页PPT)

(225页)

'模具设计技术1 DESIGN FOR MOLD ABILITY (共225页PPT)'
学习模具 设计 (一) DESIGN FOR 一MOLDABILITY ( ) 射出壓力Injection Pressure射出壓力 Injection pressure壓力驅使熔化 Pressure drives the melt Pressure is the driving force that 壓力是一種克服聚合物防熔 overcomes the resistance of polymer 化的驅動力(參照壓力驅動流 melt (see程 推進聚合物填充與保壓 Pressure-driven flow), pushing the ), polymer to fill and pack the mold 模具腔穴. 如若順著聚合物 cavity. If you熔化的流動路徑施加一些壓 place a number of pressure sensors 力感應器,你就會看到如下圖 along the flow path of the polymer 表所示的聚合物熔化壓力分 melt, the pressure distribution in the polymer 布情形. melt can be obtained, as schematically illustrated in Figure 1 below.圖 1. 壓力隨著傳送路徑與沒穴而降 ?FIGURE 1. Pressure decreases along 低. the delivery system and the cavity.? 方程式 ? Equations 基于典型的流體力學理論的單一 ? Based on a simplification of classic fluid 化, 射出壓力要求裝入傳送系統 mechanics theory, the injection pressure (注料口,流道,與水口)及洞穴能 required to fill the delivery system (the 與幾種相關材料設計與加工進程 sprue , runner, and gate) and cavities can 參數相互關聯. 在以下方程式 be correlated with several relevant 中,P 代表射出壓力; n 代表表材 material, design, and processing 料常數 (動力-法則系數), 對大多 parameters. In the following equations, P 數聚合物熔化而言 典型代表範 is the injection pressure and n is a , material constant (the power-law 圍從 0.15 到 0.36 (用 0.3最為接 coefficient), which typically ranges from 近值) 圖2 顯示了這些射出壓力 0.15 to 0.36 (with 0.3 being a good 參數的幾種功能. approximation) for a variety of polymer 圓環形水道流程 melts. Figure 2 shows injection pressure 熔化流道在澆鑄口,流道與料筒 as a function of several of these 水口處. parameters. ? Circular channel flow The melt flow in the sprue, runner, and cylindrical gates? 條形水道流程 例如熔流在淺薄的腔穴處 ? Strip channel flow Such as melt flow in a thin cavityFIGURE 2. Injection pressure as a function of melt viscosity, flow length, volumetric flow rate, and part thickness Factors that influence injection pressure requirements .The following diagrams illustrate the design and processing factors that influence injection pressure.填充模式Filling Pattern Filling pattern填充模式 What is the filling pattern?什麼是填充模式? The filling pattern is the transient 充填模式是在傳送系統與模穴內熔 progression of the melt front within the delivery system and mold cavities. It 化前段的瞬間連續推進. 它對零件 plays an important role in determining 產品的品質起著重要的決定作用. the quality ofthe part. Melt front 前段熔化速度影響充填模式 velocity influences filling pattern Constant MFV常量 MFV The ideal filling pattern has melt 理想的充填模式從頭到尾貫穿有一 reaching every extremity of the cavity 個常量的前段熔化速度 并同 simultaneously, with a (MFV) constant melt-front velocity (MFV) (see 時達到每穴填充最高熔點.(見第3 Chapter 3) throughout the process. 章)要不然,局部的過保壓會過早地 Otherwise, localized over-packing at 在零件產品上充填形成. prematurely filled regions might arise within the part.變量 MFV Variable MFV充填過程中變量熔流速度(MFV)也 A variable MFV during filling also leads 會導致當熔流塑膠接觸冷模時
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模具设计技术1DESIGNFORMOLDABILITY(共225页PPT)
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