1. A cylindrical billet that is 100 mm long and 50 mm in diameter is reduced by direct (forward) extrusion to a 20 mm diameter. The die angle is 90?. the flow curve for the work metal has a strength coefficient of 800 MPa. Determine (a) extrusion ratio, (b) true strain (homogeneous deformation), (c) ram pressure, and (e) ram force. 2. A billet that is 75 mm long with diameter = 35 mm is direct extruded to a diameter of 20 mm. The extrusion die has a die angle = 75°. For the work metal, k= 600 MPa.
Determine (a) extrusion ratio, (b) true strain (homogeneous deformation), ram pressure and (d) ram force. 3. An L-shaped structural section is direct extruded from an aluminum billet in which Lo = 250 mm and Do = 88 mm. Dimensions of the cross-section are given below. Die angle = 90?. Determine (a) extrusion ratio, (b) length of the extruded section if the butt remaining in the container at the end of the ram stroke is 25 mm. 12 62 50 12 4. Calculate the force required in extruding copper at 700C, if the billet diameter is 125 mm and the extrusion ratio is 20.
5. Calculate the extrusion force for a round billet, 200 mm in diameter made of beryllium and extruded at 1000C to a diameter of 50 mm Choose one topic only with a group of 5 members. To be submitted on the 16th December 2013 1. Handle and body of a large ratchet wrench Figure 1. 1 shows the handle and body segment of a large ratchet wrench, such as those used with conventional socket sets. The design specifications require a material with minimum yield strength of 345 MPa and an elongation of at least 2% in all directions.
Additional consideration should be given to weight minimization (because of the relatively large size of the wrench), corrosion resistance (due to storage and use environments), machinability (if finish machining is required), and appearance. Figure 1. 1 1. Based on the size and shape of the product, describe several methods that could be used to produce the component. For each method, briefly discuss the relative pros and cons. 2. What types of engineering materials might be able to meet the requirements? What would be the pros and cons of each general family? 3.
For each of the shape generation methods in question 1, select an appropriate material from the alternatives discussed in question 2, making sure that the process and material are compatible. 4. Which of the combinations do you feel would be the “best” solution to the problem? Why? 5. For your proposed solution, would any additional heat treatment or surface treatment be required? If so, what would you recommend? 6. If a variation of this tool were to be marketed as a “safety tool”, that could be used in areas of gas leaks where a spark might be fatal, how would you modify your previous recommendations in terms of material? Discuss briefly
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