BOLT Russian patent published in 2003 - IPC

FIELD: mechanical engineering. SUBSTANCE: invention relates to fastening devices. Proposed bolt has head and body with plain and threaded parts. Bolt head is of cap type. Ratio of maximum diameter of bolt head to its height is (2.4-2.6):1. Bolt head has round, oval or ellipsoidal shape in plan. Part of bolt body adjoining the head is combination, being first smooth cylindrical changing into narrowing smooth conical and then again into smooth cylindrical part. Length of each said section of bolt body corresponds to thickness of members to be connected by bolt. Ratio of diameters of cylindrical smooth parts of bolt body is 1:(0.95-0.98). smaller diameter of smooth part of bolt body is 1/10-1/12 of maximum diameter of threaded part of bolt body. Bolt is made of structural chromium steel containing by mass: 0.37-0.42% of carbon; 0.8-1.1% of chromium; 0.5-0.8% of manganese and 0.17-0.3% of silicon. Hardness of bolt after thermal treatment is 302-380 HB, ultimate tensile strength is 104-135 kgf/sq. mm, reduction of area is 35-60% and elongation is 6-16%. EFFECT: increased load-bearing capacity and improved reliability of bolt joint. 1 dwg