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US 4,539,832 AGranted
Hole sizing tool
AssigneeBalax, Inc.
InventorJoseph A. Koller
Life of this patent
Estimating the term…
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AssigneeBalax, Inc.
InventorJoseph A. Koller
Estimating the term…
A hole sizing tool uses a swaging tap to move material which deforms the sides of a generally cylindrical hole toward the axis of the cylinder and is followed by a portion of the tool having a generally flat flaced helical spiral configuration with the turns increasing in radius as the tool advances but with all portions of the surface of the helical spiral including lines parallel to the axis of the tool whereby only radial forces are exerted by said portion to force the sides of the hole gradually toward a final diameter larger than that left by the tap but smaller than the original dimension. In an alternate form of the tool the flat surfaces of the helical spiral are inclined slightly, so that the edge of such surface nearest the nose of the tap is at a slightly greater radius than the edge of the turn nearest the tool in which the tap is held, to generate a slight axial force tending to pull the tool into the work. The portion of the tool following the helical spiral is a smooth burnishing surface for the purpose of burnishing the hole to final size and finish. Both the increasing helical spiral portion and the constant size burnishing portion desirably have the periodic increases in radius (or lobes) characteristic of the threads of a swaging tap, but without thread crests and roots. If desired, the nose of the tap may have a cylindrical lead portion for alignment, particularly if the tool is not intended for blind holes.
A hole re-sizing tool comprising a shaft having an axis, said shaft having a rear driven end and a front work-entering end provided with a swaging tap section having forming threads increasing in size axially away from the front end shaped to upset the material of a work piece to at least partially form a thread, a threadless ramp surface on said tool beginning at the end of the swaging tap section furthest from the front end of the tool, said surface having the form of a helical spiral having a surface all parts of which contain substantially straight lines in the plane of said axis, the smallest turn of said ramp being directly adjacent the root of the largest turn of the swaging tap section and having substantially the same radius as said root, said helical spiral increasing in diameter in a direction along the helical spiral to a maximum diameter smaller than the maximum diameter of the crest of the thread in said swaging tap section, said ramp surface being shaped to flatten threads formed by said swaging tap section to the maximum diameter of said ramp.
The device of clam 1 in which the thread of the swaging tap lead section is provided with lobes of progressively increasing size on each turn of the thread in a direction away from said front end.
A workpiece hole sizing and burnishing tool having an axis, a driven end, and a front end, and rotatable on said axis, comprising a helical spiral swaging ramp section in which the turns have the form of a generally flat surface wound on a theoretical cone coaxial with the axis, the turns increasing in diameter away from the front end to a maximum size, and a burnishing section in which the maximum diameter remains substantially constant.
Dependencies are inferred from the claim text.