Piercing tools
OwnerJohannes Adrianus van Geffeninventor
Life of this patent
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Abstract
A rapidly rotatable piercing tool of hard material for forming by frictional heat and pressure a hole surrounded by a boss in a metal plate or the wall of a metal pipe, the pipe part for making the hole to size having basically triangular cross sectional areas the contour line of which has three outwardly curved legs of a shape to make the piercing tool expecially adapted to forcing bossed holes both in ductile and in hard metals.
Claims5
A rapidly rotatable piercing tool of hard material for forming, substantially by frictional heat and pressure, a hole surrounded by a boss in a metal plate or the wall of a metal pipe, the active part of said tool for making the diameter of the hole to size having a leading portion extending to and tapering towards the free end of the tool, said active part of the tool having cross sectional areas, of each one of which the basic shape is an equilateral triangle, each cross sectional shape consisting in and near each apex of said triangle of two arcs adjoining each other and touching the circumscribing circle of said triangle at the respective apex and of connecting lines interconnecting and blending with said arcs, the radii of curvature of said arcs being smaller than that of said circumscribing circle and the arcs which extend from the apices of the triangle in the direction of rotation of the piercing tool having a radius of curvature which is smaller than any radius of curvature of the arcs extending from said apices in the opposite direction.
Dependencies are inferred from the claim text.