Question
Download Solution PDFAcross flat dimension of hexagonal face is 20√3 mm. What is the minimum diameter of road required to machine the hexagon?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
Hexagonal nut:
- The upper corners of this nut are rounded-off or chamfered.
- The chamfering is generally conical.
- The angle of chamfer is 30° or 45° with the base of the nut.
- Due to chamfering, an arc is formed on each vertical face, and a circle is formed on the top surface of the nut.
- The dimensions of the hexagonal nut cannot be expressed exactly in terms of the nominal diameter of the bolt.
- For elementary work, the following approximately standard dimensions may be adopted
- If D = the nominal diameter of the bolt, then:
- Thickness of the nut, T = D
- Width across flats, W = 1.5D + 3 mm
- Angle of chamfer = 30°
- Radius of chamfer arc, R = 1.4D (approx.)
- Very often, and especially when a nut is shown in one view only, the following rough rule dimensions are used:
- Thickness of the nut, T = D
- Distance across diagonally opposite corners = 2D
- Angle of chamfer = 30°
- Radius of chamfer arc, R = 1.5D
Calculation:
Given:
Across flat dimension of the hexagonal face is 20√3 mm
∵ Width across flats, W = 1.5D + 3 mm
⇒ 1.5D + 3 = 20√3
⇒ D = 21 mm
∴ The nominal diameter of the bolt = 21 mm
∵ Distance across diagonally opposite corners = 2D = 2 × 21 = 42 mm
∴ The minimum diameter of the road required to machine the hexagon will be 40 mm (the nearest value amongst the given options)
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