hw3assignment

# hw3assignment - sketches of each process step and then...

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MAE4500 HW3 Due Date: Thursday April, 6 2006 (1) A water meter part is to be made by casting. The following materials are considered: Al-3%Si and Al-12%Si. a) Copy the Al-Si equilibrium diagram and identify all phase fields. b) Make two sketches showing the solidification of each of the above two alloys in cylindrical molds (type of crystals, solidification shrinkage). c) Make judgments on each material whether it will be: i. Prone to alloying element segregation. ii. Suffer from micro porosity. iii. Easy to feed. iv. Of high fluidity. (Give your answers for each material in the above sequence; justify each answer in one sentence). d) On the above basis, evaluate each material for its suitability for casting. (2) A gear blank (Fig. 1) is to be made by forging. The blank material is D2 tool steel (1.5% C, 12% Cr, 1% Mo). An initial work piece with 175 mm diameter is upset first at 1000 ° C in a press speed of 0.5m/s with graphite lubricant. A hole of 50 mm diameter is then pierced by forging at the same temperature and speed. Make

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Unformatted text preview: sketches of each process step and then calculate: a. The starting length of the work piece. b. The die pressure and forging force for each operation. c. What changes in die pressure and forging force would occur if the upsetting process is conducted at room temperature? Figure 1. 50 100 50 250 (3) An internal combustion engine valve with a stem of 10mm diameter is pre-formed by extruding a 25mm dia. 50mm long H13 steel bar at 1000 ° C on a press with v o =0.5m/s through dies with 2 α =120 ° included die angle and a glass-type lubricant (assume m*=0.1). Extrusion is interrupted to leave a 20mm long head. a. Make a dimensioned sketch of the process at the point of stopping the punch. b. Calculate in systematic manner the punch pressure at this point. c. Calculate the press force. d. Check whether there might be danger of center burst defect. If the answer is yes, suggest a remedy....
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hw3assignment - sketches of each process step and then...

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