Conceptual design and evaluation feasibility study Design analysis
• 產品設計及製造流程 • • Conceptual design and evaluation ; feasibility study. • 產品定義及 市場調查 產品概念設計 及可行性評估 設計分析(產品 Design analysis; codes/seanded review physical and analytical 分析模型及實體 模型) models. Prototype production ; easting and evaluation • Detrition of product need marketing information maybe new product or revised products. Prototype 原型 製作與測試評估 ( Including: forces,stresser deflection ,and optimalpart shape. Computer- aided Design(CAD)
Cuality control either at this slage or periodically during production. These is an important aspect of Product drawings; Instruction manuals Product drawings; product manut. Instruction manuals (better way control through out the manufacturing process) (修正產品的設計,材料選 用or製造方法) Material specification;process and equipment selection;safety review Computer aided manufacturing and process planning. (CAM and CAPP) Pilot production Production Computer inter manufacturing. (CIM) Inspection and quality Assurance Packaging market and Sales literature Product
製造程序的分類 1. 改變材料形狀的加 :casting,cold forming,hot forming, rolling,forging,extrusion,drawing, power metallurgy,injection molding. 2. 按尺寸切削加 :a. turning,boring(搪),drilling, milling, grinding,hobbing,routing(切槽) b. 非傳統: ultrasonic(超音波),electrical discharge(放電加 ),optical lasers(雷射 切割),eolectro arc rasive jet maching(磨 料 噴射切削), 3. Joint(聯結):a. welding(熔接),b. soldering(軟焊), c. brazing(硬焊),d. sintering(燒結) , e. pressing(壓接),f. riveting(鉚接), g. screw fastening(螺絲接), h. adhesive joining(黏接). 4. Finishing operation(表面加 ):polishing(磨光),honing (搪磨),lapping(研磨), surface treating coating.
鑄造程序圖 Molding――Pattern making、Core making、Gate making ↓ Sand → Mold ↓ Melting of →Pouring into →Casting →Heat treatment →Cleaning →Inspection metal Furnace mold Solidification & finishing shake out Removal of risers and gates. Defects Additional heat pressure treatment. tightness dimensions
2. 6 Sand molding Machine a. Squeezer machine b. Jolt Machine c. Jertical flaskles molding d. Sandslinjers e. Impact molding f. Vacumm molding 2. 7 Defects ( 7種basic cateqories of casting defects) a. Metallic Project:金屬毛邊,膨脹,粗糙表面。 b. Catities:收縮造成的空洞or gases產生。 c. Discontinuities:裂縫crack,cold or hot造成的撕裂。由於金 屬被constrainted因為收縮(shrinkage freely) d. Defective surface:surface folds,laps,scars,oxide scale. e. Incomplete costing,such as misnur,premature solification. f. Incorrect dimensions:owing two factors suchees,impwper shrinkage allowance,Pattern mouasting enor,irreqular contraction ,deformed pattern,casting warped. g. inclusions:form dwring meeting,solidification,and molding. 非金屬的大多有毒,or熔融金屬和氧所生之氧化物 or在熔鍋所呈的化學反應。礦渣Reaction b∕w金屬 和砂模材料。 (承b)在thicker region,由於contraction,在suface會產生”多 孔”povous. ∵收縮產生的cavitiey,可以chills來改善之, 即放至金屬在thicker region來增冷卻速率。共分二種: external and internal(和熔融金屬同材質但會有熔代問題)
2. 9 Fluid Flow And Heat Transfer ․Successful costing requires careful design and control of the solidification of the molten metal to ensure the adequate fluid flow in the system. ․Good design of gating system for trapping contaminates. 2. 9. 1 Bernoulli's theory h+ p∕ρg+ v×v∕ 2 g= constant 2. 9. 2 Continuity Q=A 1 V 1=A 2 V 2 2. 9. 3 Reynold's number Re=νDρ╱η 2. 9. 4 Heat transfer. 豎口銷的cross section須decrease as the height is lower. 否則會出 現liquid loses contact with mold wall而導致 aspiration的產生
三、現代鑄造法 A. 金屬模中的鑄造法。Method of casting in metallic molds. B. 離心鑄造法。Centrifugal casting. C. 精密or包模鑄造。Precision or investment casting. D. 連續鑄造。Continuous casting. 3. 1 Shell Mold: ․能provide good tolerances and good surface finished at low cost. 1. 將金屬製(鐵or鉛)的pattern加熱 175~ 370℃ 2. 丟入dump box,其內含細乾砂混合酚樹酯去coat the heated metal pattern. (5~ 10 mm) 3. 放入oven中for short period to cure it (使結實) 4. 製作另一patternly fallow the same manner 5. bonded or damped together 6. 裝入模箱中,相互支撐or以砂粒墊底 7. 澆鑄 advantage:需較少的製模技術,砂的用量少(5%),容易 自動化,清理成本低,表面光滑。 disadvantage:金屬樣模製造or加熱成本貴,但可大量製作, ∴依然便宜。 ☆∵用find sand,∴有lower permeability Applications:Gear housing,Cylinder head,connecting rods.
3. 2 Sodium silicate Process (CO 2 mold hardening process) 利用CO 2即矽酸鈉荃黏劑(1. 5~ 6%)來硬化模型。 →將矽酸鈉和模砂混合,塗於pattern上,then吹入CO 2來 硬化之。 ☆hardening time is about 15~ 30 seconds. 3. 3 Evaporative Pattern Casting (可消失)模法or(蒸發)模法 鋁模→注入合成樹脂polystyrene →取出樹脂模→pattern is coated with water based slurry→ dry it→置入砂模→澆注 優點: 1. 簡單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
3. 4 Plaster Mold Casting( have very low穿透性) 石膏製模,會加silica flow to improve strugttr 石膏粉+矽粉+水→塗覆於pattern(halves)上 →[15 min]→remove pattern→ dry with 120~ 260°(去水 分)→合併石膏模得模穴mold cavity→澆注pouring low穿 透性,氣體無法釋放,∴澆注需在vacuum下or under pressure 改善穿透性: 1. 可藉Antioch process:在高壓汽爐內 10 hrs去 水,12 hr rehydrated 使石膏粒狀化,具透 氣性 2. 使用foamed plaster,(即加入泡沫劑), 使得到較佳的透氣性 優點: 1. accuratc dimension 2. batter surface 3. 通常用於高溫合金(如黃銅),∵高溫時金屬模壽命 相當短,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較少摺曲worpage ☆Precision casting:plaster casting,ceramic mold and investment casting.
3. 5 Ceramic Mold Casting陶瓷模 類似石膏模,差別在於其選用耐高溫的模材 slurry is a mixture of 細鋯石+氧化鋁+熔融矽 程序: 熔融slurry→覆於pattern上→分離mold→[乾燥]→除去揮發物質 →結合上下mold→澆注 3. 6 Investment Casting(包模製造)or失臘法(lost wax) 原為 16 th century藝術家採用的方法 1. pressing wax into a split mold (鋼or brass做成欲鑄零件之複製品,再做成鉍or鉛的對合鑄模) 2. Pattern gated together to form a cluster pattern (可將n個帶有澆口,冒口的樣模組合起來) 3. Metal flask is placed outside of pattern 4. (Refractory mold slurry is poured) Dip the pattern in the slurry several time until a coat is built up. 5. melt out the wax(90~ 175℃) (then,加熱 65~ 1050℃ for 4 hrs,depending on the metal to be cast) 6. pouring molten metal 7. shake out *包模程序相當昂貴,適合高熔化溫度合金及需要good surface finish and close tolerance者 優點: 1. 可鑄造complex形狀的 件 2. 可得沒有分離線的極光滑表面 3. 尺寸準確性佳 4. 無法切削的零件,可鑄成預設之零件形狀
3. 7 Vacuum Casting 3. 8 Permanent Mold Casting (適用於低熔點金屬ex:Al, Mg,copper alloy,gray iron) 利用gravity來澆注。 Mold由耐火材料製成,如cast iron,brone,graphite or refractory metal alloys可得good surface,close tolerance uniform and good mechanical properties castings at high production rate. 常見產品為活塞頭連桿(太複雜的形狀,則取件不易,但可配 合sand core來做) 3. 9 Die casting壓鑄法 developed in 1900 S(pressure die casting在Europ稱) permanent mold casting的一種。可分為Hot chamber process and cold chamber process二種。 約於 0. 7~ 700 Mpa(0. 1~ 100 K$I)壓力下,將Molten Metal鑄 入金屬模內。
Forming and Sharping Process and Equipment 鑄件完成後須精製到成品,可藉由deformation process(ex:nod to product). 此外亦也經由粉末冶金方式 來成型。 Forming process:改變素材(solid body)的形狀(加 ) Sharping process:involves molding & casting. ˙內容將包括:滾製rolling、擠製extrusion、拉製 drawing、鍛造forging、粉末冶金power metallurgy.
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