hmewrk_03_04 - Homework #3: Metal Cutting 2.008 Design and...

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Homework #3: Metal Cutting 2.008 Design and Manufacturing II Spring 2004 Out: February 25 th Due: March 3 rd Problem 1: (a) Consider the Merchant’s Cutting Force diagram in Figure 1 and the chip-workpiece interface during orthogonal cutting in Fig. 2. α φ R F t F c F n F s F N α β β−α Fig 1. Merchant’s diagram Fig 2. Cutting FBD Merchant’s hypothesis is that the shear plane is located to minimize the cutting force, or where the shear stress is maximum. Derive the Merchant’s relationship between shear angle, rake angle, and friction angle as below from the diagram above. o α β φ = 45 + 2 2 (b) Consider the directions of the cutting force and the thrust force. Fc, cutting force, is always positive, since the material is removed. Is the thrust force, Ft, also positive at all times? If not, explain why. Also explain how you can make Ft = 0 for a given friction coefficient between the tool and the work piece.
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Problem 2: Your lab group decided to make fancy transparent-look Yo-Yos and designed the body of the Yo-Yo to be injection molded as follows. For a solid look, two identical parts are
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This note was uploaded on 02/23/2012 for the course MECHANICAL 2.008 taught by Professor Jung-hoonchun during the Spring '04 term at MIT.

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hmewrk_03_04 - Homework #3: Metal Cutting 2.008 Design and...

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