螺紋精度及換算的課件

1、Screw threads 扣件之螺紋精度等級先學(xué)會計算三角形面積S 對邊e 對角302/3SS = 11/3SABC三角形ABC面積= (1 /3S X S)=1 /23 S2計算六角形面積公式30ABC六角形面積= 1 /23 S2 X 3= 3/2 S2 = 0.866025 S2三角形ABC面積= (1 /3S X S)=1 /23 S2 Nut thread螺紋有效徑計算Pitch Dia. = D - 2 X 3/8H = D - 3/4 X 0.866025P = D - 0.649519P Bolt thread60o螺距 p有效徑陽螺紋大徑(螺絲外徑)陰螺紋小徑(螺帽孔徑)1

2、/4 H1/8 H HH = 0.866025 PMajor Dia.Pitch Dia.Minor Dia.1/2 H3/8HP.D. = D 0.65PHexagon nuts weight calculationS 對邊m厚度六角螺帽重量 g/pc= (六角面積 - 圓面積) X 厚度 X 7.85g/1,000圓面積 = /4 X Pitch Dia.2Thread designationM8 - 6g公差等級公差位置H,G,.大寫字母表示正公差 (螺帽)g,h,.小寫字母表示負公差 (螺絲)M12 X 1.75 粗牙M12 X 1.5 細牙M12 X 1.25 極細牙#10-24UN

3、C 粗牙#10-32UNF 細牙Thread tolerance position-Metric5H7H6HZero Line 基準線（零線）4h6g8g電鍍餘隙 AllowancegfNut threadBolt threadThread tolerances of ANSI (Pitch Diameter)Nut threadBolt thread+ 50+ 0+100+150+200-200-150-100- 50m2A301325/16 UNC2B1355/16 UNC1466g28M8PlainANSI6H160M8DIN3A753B981B200Allowance for plat

4、ingZero Line 基準線（零線）1A15430Thread tolerances of JIS (Pitch Diameter)6H160JIS/DIN1466g28+ 50+ 0+100+150+200-200-150-100- 50mOld JIS二級二級Size: M81304015080一級40190三級190三級80一級Nut threadBolt threadSpecial thread tolerances6e : For parts which require more room for plating8g : For semi-finished bolts (as:

5、DIN571 Carriage bolts)5g6g: For socket head cap screws strength class 12.9 (strength class 8.8 and stainless steel have 6g tolerance) Other socket products have 5g6g also (6g for stainless steel) - The first tolerance symbol applies to the pitch diameter, the second symbol applies to the major diame

6、ter4g6g: ANSI has specified 4g6g for socket products (it is relatively close to the 3A tolerance)Tolerance positionABCHGJsPRZCZT+-0ajsgpbrhzzc孔公差帶之位置軸公差帶之位置+-0Type symbol of threadDDDDDTrilobular cross- section:everywhere the same diameter Note: A threaded hole which been formed by thread forming sc

7、rews can be assembled with a machine screw Taptite (Thread forming screws for metals)常用螺紋節(jié)距規(guī)則M61.0M81.25M50.8M40.7M30.5M101.5M162.0M142.0M121.75M202.5Metric thread:Inch thread:1/420UNC1/213UNC3/816UNC5/811UNC3/410UNC#632UNC#832UNC#1024UNC18UNC#836UNF#1032UNF#640UNF1/428UNF1/220UNF3/824UNF5/818UNF3/416UNF112UNFTechnical dataEstimate of screw diametersFAFA(1)Estimate of screw diameters(2)(4)(3)2 steps4 steps1 stepHow to order fasteners Determine nominal dimensions Check tolerances of each dimension Material, quality strength, surface treatment Class marking Tooling cost, sample