JNTU
JNTU B.Tech II MACHINE DRAWING 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
Draw the sectional front view and top view of two 20 mm thick plates fastened together by means of 20 mm diameter stud, a hexagonal nut and washer. Insert important dimensions.
Answer
A stud is a headless bolt with threads on both ends. For two 20 mm thick plates, the stud is screwed into the bottom plate. The total thickness to be fastened is 40 mm. The stud diameter (d) is 20 mm. The length of the threaded portion in the bottom plate is typically 1.25d to 1.5d (25-30 mm). The nut height is 0.8d (16 mm) and the washer thickness is 0.15d (3 mm).
In the sectional front view, show the two plates with hatching lines in opposite directions. The stud passes through the top plate clearance hole and is threaded into the bottom plate. The hexagonal nut is placed on top with a washer. In the top view, the hexagonal nut is represented by two concentric circles (the outer circle is the hexagon across corners, and the inner is the chamfer circle) and the stud shank is shown as a circle with the thread root diameter.
Sketch the profile of triangular thread. Show the angle of the thread and dimension the depth, assuming a pitch of 10 mm.
Answer
The triangular thread (ISO metric thread) has an included angle of 60 degrees. For a pitch (p) of 10 mm, the dimensions are calculated as follows:
- Pitch (p) = 10 mm
- Depth of thread (H) = 0.866 × p = 8.66 mm
- Height of engagement (h) = 0.6134 × p = 6.134 mm
The profile is drawn as a series of equilateral triangles with a 60-degree angle at the crest. The crest is truncated by 1/8th of the height (H/8) and the root is rounded or truncated by 1/4th of the height (H/4). The depth of the thread is measured vertically from the crest to the root.
Two square rods of side 50 mm each, are connected by a cotter joint with a gib. Sketch the following views of the assembly:
Half sectional view from the front
Answer
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View from the side.
Answer
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Draw the sectional front view and top view of single riveted butt joint with double straps chain type to join two plates of 20 mm thickness each.
Answer
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Sketch two views of a foot-step bearing to support a 50 mm diameter vertical shaft. Show the important dimensions on the sketch.
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PART - B
The part drawings of a blow-off cock are shown in the figure below. Assemble the parts and draw the sectional front view and top view.
Answer
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