ASME B18.2.3.9M:2001 pdf download METRIC HEAVY HEX FLANGE SCREWS
4 TERMINOLOGY
For definitions of terms relating to fasteners or fea.tures thereof used in this standard, refer to ASMEB18.12.
5 DIMENSIONS
(a) All dimensions in this standard are given inmillimeters (mm), and apply before any coating,unlessstated otherwise.
(b) Symbols specifying geometric characteristics arein accord with ASME Y145M.
6 TOP OF HEAD
The top of head shall be either full form or indentedat manufacturers option. and shall be either chamferedor rounded, The diameter of the chamfer circle or startof rounding shall be equal to the maximum widthacross flats,S maximum, within a tolerance of -15%If the top of the head is indented, the periphery maybe rounded.
7 HEAD HEIGHT
The head height. K. is the distance. parallel to theaxis of the screw. from the plane of the bearing circleto the top of the head, not including any raised markingsSee para. 22.
8 WRENCHING HEIGHT
The wrenching height, K w , is the distance at a corner of the hexagon from the junction of hex head with the flange to the last plane of full-formed hexagon (i.e., the plane closest to the top of the head at which the width across corners, E, of the hexagon is within its specified limits).
9 CORNER FILL
The rounding due to lack of fill at the six cornersof the head shall be reasonably uniform.
10 GAGING OF HEAVY HEX FLANGE HEAD
See Table 1. The head shall be gaged using tworing gages,A and B.to demonstrate the coincidentalacceptability of wrenching height, corner fill, and widthacross corners. Gage A shall be placed over the headand shall seat on the flange. Gage B shall be placedon the top of the head normal to the screw axis. Thetwo gages shall not be in contact.
11 POSITION OF HEAD
At maximum material condition, the axis of thehexagon of the head shall be within a positional toler-ance zone of the diameter specified in Table 2 withrespect to the axis of the shank over a distance underthe head equal to the nominal screw diameter, D. Thedatum shall be as close to the head as practicable, butwithin 0.5D from the head. and shall be either whollyplain body or wholly the thread pitch diameter, notincluding the thread runout or the underhead fillet.
12 FLANGE
The top surface of the flange shall be conical orslightly rounded (convex). Radius, R2, applies both atthe corners and at the flats of the hexagon. The contourof edge at flange periphery, between the maximumflange diameterDmaximumand the minimum bearingcircle diameter,D minimum, shall be optional providedthat the minimum fange edge thickness, C minimum.is maintained at the minimum bearing circle diameter,0..minimum.
13 BEARING SURFACE
The bearing surface shall be conical, 0.75 +0.50 degconcave from the plane formed by the bearing circlediameter. The plane formed by the bearing circle shallbe perpendicular to the axis of the shank, over a lengthunder the head equal to the nominal screw diameter.D, within the circular runout as specified in Table 2.The measurement of bearing face runout shall be madeat the actual bearing circle (i.e., at the line of highestpoints on any radial line, e.g., by use of straight edgeanvil). The datum shall be as close to the head aspractical, and shall be either wholly plain body or
ASME B18.2.3.9M:2001 pdf download
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