三针法测量螺纹及三针选择

BSP

Thread

Measuri

ng

Whitworth

Form Wire

Selection Designatio

n Variable units

n pitch t.p.i.Smallest wire dia. 0.54P

M 3 wire measurement "Largest wire dia. 0.76P

G Wire diameter "M = O/D

- 1.6008

P +

3.1657 G

Dia. For pitch-

line contact

0.56368P

E Effective diameter "

O/D Thread OD "Pitch Smallest wire Largest wire Pitch-line Thread depth

(t.p.i.)wire

Thread Crest Diameter Pitch 3 Wire Measurement 'M'( " )( " )( " )( " ) (O/D) ( " )( t.p.i. )( " )110.04910.06910.0512440.0582

1/8" BSP0.383280.3945140.03860.05430.0402630.0457

1/4" BSP0.518190.5277190.02840.04000.0296670.0337

3/8" BSP0.656190.6992260.02080.02920.0216800.0246

1/2" BSP0.825140.8381280.01930.02710.0201310.0229

5/8" BSP0.902140.9151

3/4" BSP 1.04114 1.0541

7/8" BSP 1.18914 1.2021

1" BSP 1.30911 1.3257

1 1/4" BSP 1.6511 1.6667

1 1/2" BSP 1.88211 1.8987

2" BSP 2.34711 2.3637

1/2" BSP thread 1 1/4" BSP thread

3/4" BSP thread 1 1/2"

BSP

thread

BS EN ISO

228-1: 2003

Table 1 Thread

dimensions

1" BSP thread 2" BSP

thread

British Pipe

Thread (

Whitworth

Form) --

Parallel

(BSPP/BSPF) -

- (G)

Desig-

nation of

thread

Number of

threads in

25.4 mm Pitch P

Height of

thread h major d = D pitch d2 = D2

minor d1 =

D1

Lower

deviation

Upper

deviation

Lower

deviation

Class A

Lower

deviation

Class B

Upper

deviation

Lower

deviation

Upper

deviation

Lower

deviation

Upper

deviation

1/16280.9070.5817.7237.142 6.56100.107-0.107-0.214000.282-0.2140

1/8280.9070.5819.7289.1478.56600.107-0.107-0.214000.282-0.2140

1/419 1.3370.85613.15712.30111.44500.125-0.125-0.25000.445-0.250

3/819 1.3370.85616.66215.80614.9500.125-0.125-0.25000.445-0.250

1/214 1.814 1.16220.95519.79318.63100.142-0.142-0.284000.541-0.2840

5/814 1.814 1.16222.91121.74920.58700.142-0.142-0.284000.541-0.2840

3/414 1.814 1.16226.44125.27924.11700.142-0.142-0.284000.541-0.2840

7/814 1.814 1.16230.20129.03927.87700.142-0.142-0.284000.541-0.2840

111 2.309 1.47933.24931.7730.29100.18-0.18-0.36000.64-0.360

1 1/811 2.309 1.47937.89736.41834.93900.18-0.18-0.36000.64-0.360

1 1/411 2.309 1.47941.9140.43138.95200.18-0.18-0.36000.64-0.360

1 1/211 2.309 1.47947.80346.32444.84500.18-0.18-0.36000.64-0.360

1 3/411 2.309 1.47953.74652.26750.78800.18-0.18-0.36000.64-0.360

211 2.309 1.47959.61458.13556.65600.18-0.18-0.36000.64-0.360

2 1/411 2.309 1.47965.7164.23162.75200.217-0.217-0.434000.64-0.4340

2 1/211 2.309 1.47975.18473.70572.22600.217-0.217-0.434000.64-0.4340

2 3/411 2.309 1.47981.53480.05578.57600.217-0.217-0.434000.64-0.4340

311 2.309 1.47987.88486.40584.92600.217-0.217-0.434000.64-0.4340

3 1/211 2.309 1.479100.3398.85197.37200.217-0.217-0.434000.64-0.4340

411 2.309 1.479113.03111.551110.07200.217-0.217-0.434000.64-0.4340

4 1/211 2.309 1.479125.73124.251122.77200.217-0.217-0.434000.64-0.4340

511 2.309 1.479138.43139.951135.47200.217-0.217-0.434000.64-0.4340

5 1/211 2.309 1.479151.13149.651148.17200.217-0.217-0.434000.64-0.4340

611 2.309 1.479163.83162.351160.87200.217-0.217-0.434000.64-0.4340

Note:

Class B

applies

only to

external

threads.

Internal

threads

are Class

A.

BS EN

ISO 228-

1: 2003

data chart

above

revised

and

updated

12/20/11

External thread Td2Internal thread TD1

Tolerances on pitch diametera Tolerance on minor Tolerance on major

External thread Td

Diameters Internal thread TD2