CLAMP BOLTS MANUFACTURING METHOD Russian patent published in 2007 - IPC B21K1/46 B21K7/10 

FIELD: plastic working of metals, possibly manufacture of clamp bolts for rail fastenings of railroad tracks by cold forging in multiple automatic presses.

SUBSTANCE: bolts are made for four transitions. At first transition head of bolt in the form of truncated cone and cylindrical portion on head end are preliminarily formed. Diameter of said cylindrical portion consists of 0.95 - 0.98 of ready head ready size. Height of said portion consists of 0.2 - 0.3 of height of bolt head. At second transition head with spherical supporting surface is formed and end protrusion with cross section in the form of rectangle is formed. Width of said protrusion is equal to size of ready head and its height consists of 0.2 - 0.3 of height of bolt head. At third transition bolt stem is reduced for knurling thread. At fourth transition two faces of head are trimmed for head ready size; trimming is realized by feeding trimming tool in the form of punch and die at side of head end and at side of spherical supporting surface. Punch with hole is used for arranging in hole of protrusion of head end formed at second transition.

EFFECT: lowered metal consumption, improved strength of tool.

3 dwg