a) (2 marks for each part) Clearly indicate one preferred method of metal remova
ID: 2087458 • Letter: A
Question
a) (2 marks for each part) Clearly indicate one preferred method of metal removal in your choice of the following situatio involving steel members i) the teeth on an internal gear (teeth cut on the inside surface of the blank, before hardening), ii) the final finish for a needle roller bearing surface on a 1050 (G10500) CD shaft, iii) the through keyway on the inside surface of a gear hub, iv) reducing the thickness of a 90 mm by 200 mm flat mild steel plate from 12 mm to 11.25 0.10 mm thickness v) a low carbon solid circular section transmission shaft, with many steps of varying depth, and suggest a steel for use in this application, vi) the final tooth shape for a hardened steel gear, if a "precision finish" is specified vii) the complex "teardrop" shape for a through port in the end plate of a hydraulic pump, b) (8 marks total) i) A gear is subjected to heavy impact loads. Clearly stating your reasons, would you design the gear with high strength, high alloy steel with no hardening, or having a medium grade steel with hardened tooth surfaces ii) In a hardened gear, what reasoning would you use in specifying either induction or carburizing? ii Under what conditions would you specify a finish grinding operation on hardened gear teeth? c) (6 marks for each part) New techniques are being developed for the building of steel car bodies i) Many body panels can be formed by using "tailored blanks". In this process, dissimilar sheets of steel are laser-welded together. Use the outer panel of a car door as one application, and consider strength, formability and environmental problems. Indicate clearly how you would design a lightweight tailored-blank door panel The complex fore-and-aft rails above the doors can be formed in one piece by the hydro- forming process. Discuss the advantages of using this process in this application. What method(s) would have been used to form this part prior to hydroforming? ii)Explanation / Answer
a)
i) Internal gears are cut using a gear shaping machine with its reciprocating motion. it's mounted with a pinion. Gear hobbing method can't be used to make internal gears.
ii) Grinding is the final finishing operation that can be used hear. If for further finish lapping or honing processes can be employed
iii) Broaching is used to create key way in gear hub. A briach us multipoint cutting tool with teeth Starting with roughing teeth and ending with finishing teeth. The material removal us gradually increasing.
iv) Slab milling is used to reduce the thickness up to 11.25+0.01 mm. If the tolerance was very tighter, one must go for surface grinding after milling up to 11.3 mm.
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