JNTU
JNTU B.Tech II Year MACHINE DRAWING AND COMPUTER AIDED GRAPHICS Previous Question Paper (September/October - 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
Draw front, side and top view of a hexagonal bolt of diameter 30 mm and length 100 mm along with its nut.
Answer
To draw a hexagonal bolt and nut assembly with a nominal diameter (d) of 30 mm and length (L) of 100 mm, follow these standard proportions:
- Bolt Head: The width across flats (W) is 1.732d ≈ 52 mm, and the height (k) is 0.7d = 21 mm. The chamfer angle is 30 degrees.
- Nut: The height of the nut (H) is 0.8d = 24 mm. The width across flats is the same as the bolt head (52 mm).
- Threaded Length: The length of the threaded portion (l) is typically 2d + 6 mm = 66 mm.
- Views:
- Front View: Draw the bolt head and the shank of 100 mm length. Show the nut tightened against the head or at the end of the thread. Include the chamfer arcs on the hexagonal faces.
- Top View: Draw a regular hexagon with a circle of diameter 30 mm inside representing the shank, and a larger circle representing the core diameter of the thread.
- Side View: Project the hexagonal profile from the top view to show the flats of the bolt head and nut.
Draw two views of a single riveted butt joint with a double cover plate for a plate thickness of 12 mm.
Answer
For a plate thickness (t) of 12 mm, the design parameters for a single riveted double cover butt joint are as follows:
- Rivet diameter (d): Using Unwin's formula, d = 6√t = 6√12 ≈ 20.78 mm. Adopt d = 21 mm.
- Thickness of each cover plate (tc): Usually 0.625t = 0.625 × 12 = 7.5 mm.
- Pitch (p): For a single riveted joint, p ≈ 3d = 3 × 21 = 63 mm.
- Margin (m): m ≈ 1.5d = 1.5 × 21 = 31.5 mm.
The two views required are the longitudinal sectional view and the top view (plan):
- Longitudinal Sectional View: Draw the two main plates with a butt joint. Place the two cover plates (each 7.5 mm thick) on either side. Show the rivet head (snap head) with a diameter of 1.6d (approx. 34 mm) and height of 0.7d (approx. 15 mm). The section lines should be drawn on the plates and the rivet shank.
- Top View: Draw the edges of the main plates and the cover plates. Show the center line of the rivet row. Represent the rivet heads as circles of diameter 1.6d. Indicate the pitch distance between rivets along the joint line.
Ensure all dimensions are clearly marked on the drawing, maintaining proper scale and standard conventions for riveted joints.
Sketch a suitable pipe joint to connect two pipes, each of diameter 500 mm. The pipes are to be laid underground. Indicate proportionate dimensions of various parts of the joint.
Answer
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Draw the half sectional F.V and top view of sleeve and cotter joints to connect of two Rods of 30 mm diameter.
Answer
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PART B
Assemble all parts of the stuffing box for a vertical steam engine, shown in figure and draw, All dimensions are in mm.
Half sectional view from the front, with left half in section,
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Half sectional view from the right and view from above.
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