PPT《制造：一种将材料成型转换成产品的过程,其包含产品设计 ...》

s theory h+ pMρg+ v*vM2g= constant 竖口销的cross section须decrease as the height is lower.否则会出 现liquid loses contact with mold wall而导致 aspiration的产生 2.9.2 Continuity Q=A1V1=A2V2 2.9.3 Reynold'

s number Re=νDρη 2.9.4 Heat transfer. A.金属模中的铸造法.Method of casting in metallic molds. B.离心铸造法.Centrifugal casting.C.精密or包模铸造.Precision or investment casting.D.连续铸造.Continuous casting.3.1 Shell Mold: ?能provide good tolerances and good surface finished at low cost.1.将金属制(铁or铅)的pattern加热175~370℃2.丢入dump box,其内含细乾砂混合酚树酯去coat the heated metal pattern.(5~10mm)3.放入oven中for short period to cure it (使结实)4.制作另一patternly fallow the same manner 5.bonded or damped together6.装入模箱中,相互支撑or以砂粒垫底7.浇铸

三、现代铸造法 advantage:需较少的制模技术,砂的用量少(5%),容易 自动化,清理成本低,表面光滑.disadvantage:金属样模制造or加热成本贵,但可大量制作,依然便宜.∵用find sand,∴有lower permeabilityApplications:Gear housing,Cylinder head,connecting rods. 3.2 Sodium-silicate Process (CO2 mold hardening process) 利用CO2即矽酸钠荃黏剂(1.5~6%)来硬化模型.将矽酸钠和模砂混合,涂於pattern上,then吹入CO2来 硬化之. hardening time is about 15~30 seconds. 3.3 Evaporative Pattern Casting (可消失)模法or(蒸发)模法 铝模→注入合成树脂polystyrene →取出树脂模→pattern is coated with water-based slurry→ dry it→置入砂模→浇注 优点: 1.简单process 2.cheap flask can do it 3.型模easy且easy for complex pattern 4.easy cleaning and finishing 5.for long run it is very economical major factor is the cost for producing the die 6.process can be automated 优点: 1.accuratc dimension 2.batter surface 3.通常用於高温合金(如黄铜),∵高温时金属模寿命 相当短,石膏只使用一次,∴nothing to worry about 4.∵plaster has low thermal conductivity,and casting cool slowly and more uniform grain structure,casting较少摺曲worpage Precision casting:plaster casting,ceramic-mold and investment casting. 3.4 Plaster-Mold Casting( have very low穿透性)石膏制模,会加silica flow to improve strugttr 石膏粉+矽粉+水→涂覆於pattern(halves)上→[15min]→remove pattern→ dry with 120~260°(去水 分)→合并石膏模得模穴mold cavity→浇注pouring low穿 透性,气体无法释放,∴浇注需在vacuum下or under pressure 改善穿透性:1.可藉Antioch process:在高压汽炉内10hrs去水,12hr rehydrated 使石膏粒状化,具透 气性 2.使用foamed plaster,(即加入泡沫剂)使得到较佳的透气性 3.6 Investment Casting(包模制造)or失腊法(lost wax) 原为16th century艺术家采用的方法 1.pressing wax into a split mold (钢or brass做成欲铸零件之复制品,再做成铋or铅的对合铸模) 2.Pattern gated together to form a cluster pattern (可将n个带有浇口,冒口的样........