din-6912-vint参考标准资料

UDC621.882.215.61.091.1May 1985Hexagon socket thin head cap screwsDINwith pilot recess for wrench key6912Zylinderschrauben mit Innensechskant:niedriger Kopf.mit SchlusselfuhrungSupersedesDecember 1967 edition.In keeping with current practice in standards published by the International Organization for Standardization (ISO),a commahas been used throughout as the decimal marker.Dimensions in mm1 Field of applicationThis standard specifies product grade A hexagon socket thin head cap screws with pilot recess for wrench key with ISOmetric screw thread from M4 up to and including M36.If,in special cases,the screws are to meet requirements other than those given in this standard,e.g.with regard to propertyclass or material.these shall be selected in accordance with the appropriate standard.This also applies to the fine pitchthread conforming to DIN 13 Part 13 required in exceptional cases.The critical cross section of screws covered by this standard can.as a consequence of the head geometry and the form ofthe wrench engagement,be located below the hexagon socket and not in the thread.This particularly applies for fine pitchthread screws and/or where tolerance positions are unfavourable (see also Explanatory notes).It is thus recommendedthat the screws should not be used for the transmission of high axial loads involving prestressing.These screws can not be used in the form of screw assemblies with captive washers as specified in DIN 6900.as they arealways required to have a short unthreaded portion of shank to compensate for the pilot recess,taking into accountstrength criteria.2DimensionsChamfered endcomplying with DIN 78Slight rounding orcountersink at the mouth(b)of the socket permissible(no further than e).u=2 P maximum,incomplete threadDetail XBottom edge of head may be rounded orMaximum underhead filletchamfered to d.and shall be deburred.fnax=17rmaxSee table.45°max7Top of head roundedor chamfered (pressing contour).at the manufacturer's discretionContinued on pages 2 to 7281