how to solve 8

Question

4.1. an ISO screw thread of 3,5mm pitch has an effective diameter of 30mm. The three-wire method is used for checking the effective diameter. The best wire size method is used for the test wires. Calculate the micrometer reading over the three wires. 4.2.1. Explain, step by step, how you would go about checking the correctness of the teeth of a gear wheel, having a module of 10mm and pressure angle of 20 degrees, using a gear-tooth Vernier caliper and applying the constant-chord method of checking. 4.2.2. Make the necessary calculations for the above test by using the constant-chord method of checking.

Comments

Please provide Sufficient data for problem 4.2.1.

Give number of teeth(N) or pitch radius value(R).

Then we can use formula using Gear-tooth Vernier caliper method is

Gear tooth thickness w = mNsin(90/N).

Answer 1

4.1)

Effective diameter D = 30 mm

D = 30*0.0393701 = 1.1811 inch                 ( Substitute : 1 mm = 0.0393701 inch )

ISO screw thread pitch p = 3.5 mm

p = 3.5*0.0393701 = 0.13779 inch

The best wire size ( diameter ) using three-wire method is G = 0.57735p

G = 0.57735*0.13779 = 0.07955 inch

Threads per inch N = 1/p = 1/0.13779 = 7.2574

 

Micrometer reading M = D+3G-(1.5155/N)

M = 1.1811 + 3(0.07955) - (1.5155/7.2574) = 1.1811 + 0.23865 - 0.20882 = 1.21093 inch

M = 1.21093/0.0393701 = 30.7576 mm

The best wire size ( diameter ) over the three wires using three-wire method is 30.7576 mm.

Answer 2

4.2.2)

Module m = 10 mm.

Pressure angle ψ = 20º

Constant chord thickness X_c = (mπ/2)cos²ψ

X_c = (10π/2)cos²(20º) = 13.87 mm

Constant chord thickness is 13.87 mm.