JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II MACHINE DRAWING AND COMPUTER AIDED GRAPHICS Previous Question Paper (April/May - 2023 - R15)
Note: This question paper contains two parts A and B. i) Part- A for 30 marks, ii) Part - B for 45 marks. i) Part – A: 3 out of 4 questions must be answered. ii) Part – B: 1 Compulsory Question (No Choice) to be answered for 45 Marks.
PART - A
(30 Marks)
Draw sectional front view and top view for a double riveted butt joint for plates of thickness 12 mm with double cover plate and chain riveting.
Answer
For a double riveted butt joint with double cover plates and chain riveting, the design parameters for plates of thickness t = 12 mm are calculated as follows:
- Rivet diameter (d): Using Unwin's formula, d = 6.04 * sqrt(t) = 6.04 * sqrt(12) ≈ 21 mm. Standard practice adopts d = 22 mm.
- Pitch (p): For chain riveting, p = 3 * d = 3 * 22 = 66 mm.
- Margin (m): m = 1.5 * d = 1.5 * 22 = 33 mm.
- Transverse pitch (pt): For chain riveting, pt = 0.8 * p ≈ 50 mm.
- Cover plate thickness (tc): tc = 0.625 * t = 0.625 * 12 = 7.5 mm.
Sectional Front View: The two main plates are placed edge-to-edge. Two cover plates of 7.5 mm thickness are placed on either side. Two rows of rivets pass through the main plates and both cover plates. The section line passes through the center of the rivet rows, showing the rivets in section with snap heads. The main plates have a gap between them at the butt joint.
Top View: The view shows the edges of the main plates and the cover plates. Two rows of rivets are visible, aligned in a chain pattern (rivets in the second row are directly behind those in the first row). The pitch p is marked between rivets in the same row, and the transverse pitch pt is marked between the two rows.
Sketch the following types of keys in two views, as fitted in position between a shaft and the mounting. Choose the shaft diameter as 30 mm and the hub diameter of the mounting as 60 mm.
Answer
A saddle key is a friction-based key that does not require a keyway in the shaft. The shaft is usually machined with a flat surface. In the end view, the key is shown resting on the flat surface of the 30 mm shaft, with the hub (60 mm diameter) having a corresponding keyway. The longitudinal view shows the key tapering along its length, typically with a taper of 1:100, fitting snugly into the hub keyway.
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Sketch the sectional view from the front and view from the side of a split-muff coupling for connecting two shafts, each of diameter 30 mm.
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Draw the half sectional view from the front, with top view knuckle joint, to connect two rods of 30 mm diameter each.
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PART - B
(45 Marks)
Following figure gives the part drawings of Plummer block. Assemble all the parts and draw the following assembled views. All dimensions are in mm:
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