Machined 11.5 teeth per inch with CA6140 lathe

Since the US thread of 11.5 teeth per inch (25.4mm) is not given in the CA6140 machine thread feed schedule, only CNC machine tools or fitter taps can be used for machining. In the practical work, the author realized the use of CA6140 lathe to process 11.5 teeth per inch of American thread through calculation and practice.

The transmission route of the original CA6140 machine tool signage is adjusted by the Samsung wheel drive (63/100) × (100/75). If the number of teeth per inch of the inch thread is n, then n=25.4/[(58/58)×( 33/33) × (63/75) × (1/i base) × (36/25) i expansion × 12] where i is 8 types, which are 26/28, 28/28, 32/28, 36 /28, 19/14, 20/14, 23/21 and 36/21.

i is expanded into 4 types, which are (18/45)×(15/48)=1/8, (28/35)×(15/48)=1/4(18/45)×(35/28). = 1/2 and (28/35) × (35/28) = 1.

The author adjusts the Samsung wheel drive to (64/100) × (100/97), and the i base uses 36/28, i to expand (28/35) × (15/48) = 1/4.

Inch thread pitch P=25.4/n=2.208 6mm from the original formula n =25.4/[(58/58)×(33/33)×(63/75)×(1/i base)×(36/25)i Expansion × 12] brought into the adjustment of the Samsung wheel, i base, i expansion converted to the US thread pitch p'.

p '=(58/58)×(33/33)×(64/97)×(28/36)×(36/25)×(28/35)×(15/48)×12=2.216 9( Mm)

Pitch error Δ=p-p '=2.208 6-2.216 9=0.008 3(mm). Take the thread processing of NPTF1 1/2 as an example. The reference distance of 11.5 teeth per inch is 10.66mm, the number of turns is 4.83 circles, the assembly remainder is 6.626mm, the number of turns is 3 turns, and the cumulative deviation of the effective thread lead is (4.83). +3)×0.008 3=0.064(mm), the cumulative lead value of the thread lead is allowed to be 0.076mm, and the verification is 0.064<0.076mm. Therefore, this method meets the tolerance requirement of processing 11.5-tooth US thread per inch.

The handles A, B, C, D are adjusted to the handle D; the handles I, II, III, IV are adjusted to the handle II; the handles 1, 2, 3, 4, 5, 6, 7, 8 are adjusted to the handle 4.

Diffenrential Pressure Gauge

Differential Pressure Gauge