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1、BRITISH STANDARD BS 916:1953 Incorporating Amendment Nos. 1, 2, 3 and 4 Specification for Black bolts screws and nuts Hexagon for partly machined bolts a choice between medium and free fit threads is given. It will also be noted that the standard recognizes the production and usage of black screws a
2、nd the title has been amended accordingly. In adhering to the decision not to re-issue BS 28, it was realized that there are certain applications in heavy engineering work for which the use of the old large (Whitworth) size nuts might be desirable. BS 1769, “Unified black hexagon bolts, screws and n
3、uts heavy series”, may, however, meet this need, but where it does not, nuts of the basic dimensions of BS 28 will be supplied by the manufacturers when required for such applications as those referred to above. A British Standard does not purport to include all the necessary provisions of a contrac
4、t. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and iv, pages 1 to 14 and a back cover. Th
5、is standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. iv blank BS 916:1953 BSI 04-20001 1 Scope This standard relates to ferrous bolts, screws and nuts. Dimensions and certain requirements
6、are given in respect of bolts, screws and nuts which are either black all over or have partially machined finishes. The bolts, screws and nuts may be produced by hot or cold forging at the option of the manufacturer. 2 Material The steel used for the manufacture of the bolts, screws and nuts shall b
7、e such that the finished products possess a minimum tensile strength of 26 tons/sq. in. and a minimum elongation of 20 per cent of the gauge length or a minimum tensile strength of 28 tons/sq. in. and a minimum elongation of 17 per cent. The choice of either material will normally be at the option o
8、f the manufacturer except where the purchaser specifically states which of the two he requires. NOTEGauge length = 4 (See BS 18.3) 3 Finish The bolts, screws and nuts shall be neatly and cleanly made. 4 Dimensions The dimensions and tolerances of the bolts, screws and nuts shall be in accordance wit
9、h Table 1 to Table 5 inclusive. 5 Length of bolts and screws a) The nominal length of the bolts and screws shall be the distance from the underside of the head to the further end of the shank, the length of the machined point, if any, being regarded as part of the nominal length. b) The permissible
10、tolerance on the nominal length shall be as follows: 6 Ends of bolts and screws The ends of bolts and screws may, at the option of the manufacturer, be finished with either a flat chamfer with a 90 included angle to a depth slightly exceeding the depth of thread, or with a radius approximately equal
11、 to 11/4 times the nominal diameter of shank. When bolts and screws are made with rolled threads the lead formed at the end of the bolt or screw by the thread rolling operation may be regarded as providing the necessary chamfer to the end, no other machining operation being necessary, and the end sh
12、all be reasonably square with the centre line of the shank. 7 Screw threads a) Bolts and screws. For bolts and screws as forged the screw threads shall be B.S.W. free class in accordance with BS 84, “Parallel screw threads of Whitworth form”. For bolts and screws machined under the head, with or wit
13、hout turning on the shank, the screw threads may be B.S.W. or B.S.F. and may be free class or medium class, in accordance with BS 84, as specified by the purchaser. The screw threads may be cut or rolled at the option of the manufacturer. b) Nuts. For nuts as forged the screw threads shall be B.S.W.
14、 normal class and for nuts machined on one or both faces they shall be B.S.W. or B.S.F. normal class, in accordance with BS 84, as specified by the purchaser. 3) BS 18, “Tensile testing of metals”. Nominal lengthDiameterTolerance on length All lengthsBelow 1 in. 1 in. and over + 1/8in. 0 + 3/16in. 0
15、 area. BS 916:1953 2 BSI 04-2000 8 Length of thread a) Bolts. The length of the thread shall be such that when a machined nut is screwed as far as possible on to the bolt by hand, the distance between the underside of the bolt head and the nearest face of the nut shall not be more than the nominal l
16、ength of the bolt minus the values given at i) or ii) below, as applicable. i) Bolts as forged. ii) Bolts faced under the head with or without turning on the shank. Bolts that are too short for minimum thread length shall be threaded as screws. b) Screws. Screws shall be threaded to permit a standar
17、d screw ring gauge to be screwed by hand to within a distance from the underside of the head as follows: 9 Chamfering and facing a) Bolts and screws. Hexagon bolt heads and screw heads shall be chamfered at an angle of approximately 30, and square heads at an angle of approximately 25, on their uppe
18、r faces. The diameter of the ring formed by the chamfer on the upper face of the bolt or set screw head shall not be smaller than 90 per cent of the minimum across flats dimension (Figure 1). The lower or bearing face shall be machined only if specified by the purchaser. Length of bolt All diameters
19、 up to and including 1/2 in. and all drilled bolts All diameters over 1/2in. Up to and including 4 in.2 diameters11/2 diameters Over 4 in. and up to and including 8 in.2 diameters2 diameters Over 8 in.21/2 diameters21/2 diameters Length of boltAll diameters All lengths2 diameters Threads per inch Di
20、stance from underside of head 16 and under Over 16, up to and including 20 Over 20 2 pitch 21/2 pitch 3 pitch BS 916:1953 BSI 04-20003 b) Nuts: hexagon and square. These shall be chamfered at an angle of approximately 30, and square nuts at an angle of approximately 25, on one or both faces at the o
21、ption of the manufacturer. They shall be machined on one or both faces only when so specified. c) Unmachined lock nuts. These shall be chamfered to an angle of approximately 30 on one or both faces, at the option of the manufacturer. They shall be machined and chamfered on both faces only when so sp
22、ecified. NOTEThe option referred to in Sub-clauses b) and c) above shall apply unless the purchaser in his enquiry and order specifically states that he requires the nuts to be “full bearing” or “double-chamfered”. Attention is drawn to the fact that these alternative methods of finishing the lower
23、face of nuts are associated both with the nominal size and the particular method of manufacture. A request by the purchaser for a specific type of finish limits the manufacturing processes available, and it is therefore recommended that the purchaser avoids making a request for a specific type of fi
24、nish unless circumstances fully justify it. 10 Nuts: squareness of thread to face a) The bearing surface of unmachined (black) nuts shall be square to the axis of the thread of the nut within the tolerances given in Column 18 of Table 3. b) The bearing surface of machined nuts shall be square to the
25、 axis of the thread of the nut within the tolerances given in Column 19 of Table 3. Figure 1 BS 916:1953 4 BSI 04-2000 11 Diameter of shank of bolts a) The maximum diameter of the unthreaded portion of the shank of bolts shall be in accordance with the dimensions given in Column 2 of Table 1 and Tab
26、le 2. The shank diameter shall be checked by means of a plain ring gauge having a maximum thickness equal to the nominal diameter of the bolt, a minimum fillet radius in the bore equal to the maximum radius under the bolt head and an internal diameter equal to the maximum shank diameter as specified
27、 in Column 2 of Table 1 and Table 2. The internal diameter shall be subject to a tolerance of + 0.001 in., + 0.002 in. for all sizes. b) The unthreaded shank on bolts shall be machined only if stated by the purchaser in his order. When the shank is machined the limits of size shall be in accordance
28、with the dimensions given in Columns 3 and 4 of Table 2. 12 Drilled bolts and split-pin holes a) Bolts with split-pin holes will be supplied only when specially ordered; the purchaser shall specify dimension J (see Figure 14). Table 4 shows the recommended sizes of drilled holes, but if other sizes
29、are required they shall be specified by the purchaser. b) The tolerances on the specified dimension J shall be as follow: c) The split-pin holes shall be drilled through the centre of the bolt and at right angles to the axis. Washers This clause was deleted by Amendment No. 3, October, 1961. Nominal
30、 size of bolt Tolerance on dimension “J” Up to and including 5/8in. Over 5/8in. and up to and including 1 in. + 1/32 in. 0 + 3/64 in. 0 Above 1 in. and up to and including 11/2in.+ 1/16 in. 0 BS 916:1953 BSI 04-20005 Hexagon and square head bolts and screws Figure 2 Hexagon head bolt Figure 3 Hexago
31、n head screw Figure 4 Square head bolt Alternative types of end permissible on bolts and screws BS 916:1953 6 BSI 04-2000 Hexagon and square head bolts and screws Figure 5 Square head screw Figure 6 Rounded endFigure 7 Rolled thread end Alternative types of end permissible on bolts and screws BS 916
32、:1953 BSI 04-20007 Table 1 Hexagon and square head bolts and screws 1234567891011 Nominal size D Dia. of unthreaded shank B No. of threads per inch Width across flats A hex. and square Approx. max. width across corners C Radius under head R Thickness of head F hex. and square Nominal size D max.B.S.
33、W.max.min.hex.squaremax.max.basic in.in.in.in.in.in.in.in.in.in. 1/4 0.280200.4450.4350.510.63 1/32 0.1860.166 1/4 5/16 0.342180.5250.5150.610.74 1/32 0.2280.208 5/16 3/8 0.405160.6000.5850.690.85 1/32 0.2700.250 3/8 7/16 0.468140.7100.6950.821.00 1/32 0.3120.292 7/16 1/2 0.530120.8200.8000.951.16 1
34、/32 0.3630.333 1/2 9/16 0.592120.9200.9001.061.30 3/64 0.4050.375 9/16 5/8 0.665111.0100.9851.171.43 3/64 0.4470.417 5/8 3/4 0.790101.2001.1751.391.70 3/64 0.5300.500 3/4 7/8 0.91591.3001.2701.501.84 1/16 0.6230.583 7/8 11.04081.4801.4501.712.09 1/16 0.7060.6661 11/81.17571.6701.6401.932.36 1/8 0.79
35、0.7511/8 11/41.30071.8601.8152.152.63 1/8 0.890.8311/4 13/8a1.42562.0502.0052.372.90 1/8 0.980.9213/8a 11/21.55062.2202.1752.563.14 1/8 1.061.0011/2 15/8a1.68552.4102.3652.783.41 1/8 1.181.0815/8a 13/41.81052.5802.5202.983.65 1/8 1.271.1713/4 22.0604.52.7602.7003.193.90 1/8 1.431.332 21/443.1503.090
36、3.644.45 3/16 1.601.5021/4 21/243.5503.4904.105.02 3/16 1.771.6721/2 23/43.53.8903.8304.495.50 3/16 1.931.8323/4 33.54.1804.0804.835.91 3/16 2.152.003 31/4a3.254.5304.4305.236.41 1/4 2.322.1731/4a 31/23.254.8504.7505.606.86 1/4 2.482.3331/2 33/4a35.1805.0805.987.33 1/4 2.652.5033/4a 435.5505.4506.41
37、7.85 1/4 2.822.674 41/22.8756.3806.2557.379.02 1/4 3.203.0041/2 52.7507.3007.1758.4310.32 1/4 3.533.335 51/22.6258.3508.2259.6411.81 1/4 3.873.6751/2 62.59.4509.32510.9113.36 1/4 4.204.006 a To be dispensed with wherever possible. BS 916:1953 8 BSI 04-2000 Hexagon and square head bolts and screws Fi
38、gure 2 Hexagon head bolt Figure 3 Hexagon head screw Figure 4 Square head bolt Alternative types of end permissible on bolts and screws BS 916:1953 BSI 04-20009 Hexagon and square head bolts and screws Figure 5 Square head screw Figure 6 Rounded endFigure 7 Rolled thread end Alternative types of end
39、 permissible on bolts and screws BS 916:1953 10 BSI 04-2000 Table 2 Hexagon and square head bolts faced under head, and faced under head and turned on shank 1234567891011121314 Nom. size D Diameter of shank Number of threads per inch Width across flats A Approx. max. width across corners C Radius un
40、der head R Thickness of head F hexagon and square Nom. size D Faced under head Faced under head and turned on shank max.max.min.B.S.W.B.S.F.max.min.hex.sq.max.max.min. in.in.in.in.in.in.in.in.in.in.in.in. 1/4 0.2800.250 0 0.246 5 20260.445 0.4350.510.63 1/32 0.1760.156 1/4 5/16 0.3420.312 5 0.309 0
41、18220.525 0.5150.610.74 1/32 0.2180.198 5/16 3/8 0.4050.375 0 0.371 5 16200.600 0.5850.690.85 1/32 0.2600.240 3/8 7/16 0.4680.437 5 0.433 5 14180.710 0.6950.821.00 1/32 0.3020.282 7/16 1/2 0.5300.500 0 0.496 0 12160.820 0.8000.951.16 1/32 0.3430.323 1/2 9/16 0.5920.562 5 0.558 5 12160.920 0.9001.061
42、.30 1/32 0.3750.345 9/16 5/8 0.6650.6250.61911141.010 0.9851.171.43 1/32 0.4170.387 5/8 3/4 0.7900.7500.74410121.200 1.1751.391.70 1/32 0.5000.470 3/4 7/8 0.9150.8750.8679111.300 1.2701.501.84 1/32 0.5830.553 7/8 11.0401.0000.9928101.480 1.4501.712.09 1/32 0.6660.6361 11/81.1751.1251.117791.670 1.64
43、01.932.36 3/64 0.750.7111/8 11/41.3001.2501.242791.860 1.8152.152.63 3/64 0.830.7911/4 13/8a1.4251.3751.365682.050 2.0052.372.90 3/64 0.920.8813/8a 11/21.5501.5001.490682.220 2.1752.563.14 3/64 1.000.9611/2 15/8a1.6851.6251.615582.410 2.3652.783.41 3/64 1.081.0215/8a 13/41.8101.7501.740572.580 2.520
44、2.983.65 3/64 1.171.1113/4 22.0602.0001.9904.572.760 2.7003.193.90 3/64 1.331.272 21/42.2502.240463.150 3.0903.644.45 1/16 1.501.4221/4 21/22.5002.490463.550 3.4904.105.02 1/16 1.671.5921/2 23/42.7502.7403.563.890 3.8304.495.50 1/16 1.831.7523/4 33.0002.9903.554.180 4.0804.835.91 1/16 2.001.903 31/4
45、a3.2503.2353.2554.530 4.4305.236.41 3/32 2.172.0731/4a 31/23.5003.4853.254.54.850 4.7505.606.86 3/32 2.332.2331/2 33/4a3.7503.73534.55.180 5.0805.987.33 3/32 2.502.4033/4a 44.0003.98034.55.550 5.4506.417.85 3/32 2.672.574 41/24.5004.4802.87546.380 6.2557.379.02 1/8 3.002.8541/2 55.0004.9802.7547.300
46、 7.1758.43 10.32 1/8 3.333.185 51/25.5005.4802.62548.350 8.2259.64 11.81 1/8 3.673.5251/2 66.0005.9802.549.450 9.325 10.91 13.36 1/8 4.003.856 a To be dispensed with wherever possible. BS 916:1953 BSI 04-200011 Table 3 Hexagon and square nuts and hexagon lock nuts Figure 8 Hexagon nut Figure 9 Doubl
47、e chamfered Figure 10 Square nut Figure 11 Double chamfered Alternative types of hexagon nutsAlternative types of square nuts 12345678910 Nominal size D Number of threads per inch Width across flats A Approx. max. width across corners C Thickness of nut E Black Faced one side B.S.W.B.S.F.max.min.hex
48、agonsquaremax.min.max. in.in.in.in.in.in.in.in. 1/4 20260.4450.4350.510.630.2200.2000.200 5/16 18220.5250.5150.610.740.2700.2500.250 3/8 16200.6000.5850.690.850.3320.3120.312 7/16 14180.7100.6950.821.000.3950.3750.375 1/2 12160.8200.8000.951.160.4670.4370.437 9/16 12160.9200.9001.061.300.5300.5000.5
49、00 5/8 11141.0100.9851.171.430.6020.5620.562 3/4 10121.2001.1751.391.700.7280.6870.687 7/8 9111.3001.2701.501.840.8100.7500.750 18101.4801.4501.712.090.9350.8750.875 11/8791.6701.6401.932.361.0601.0001.000 11/4791.8601.8152.152.631.2051.1251.125 13/8a682.0502.0052.372.901.3301.2501.250 11/2682.2202.1752.563.141.4551.3751.375 15/8a582.4102.3652.783.411.5801.5001.500 13/4572.5802.5202.983.651.7251.6251.625 24.572.7602.7003.193.901.8501.7501.750 21/4463.1503.0903.644.451.9751.8751.875
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