Contoured punch tool for removing semi-tubular rivets

• US H419 H
• Filed: 09/30/1986
• Issued: 02/02/1988
• Est. Priority Date: 06/10/1985
• Status: Abandoned Application

• Current Assignee: Halver V. Ross
• Original Assignee: Halver V. Ross
• Inventors: Ross, Halver V.
• Primary Examiner(s): Tudor, Harold J.
• Application Number:
  US69/136,33
• Time in Patent Office: 490 Days
• Field of Search: 029275, 030358, 030360, 030361, 030366, 030367, 030368, 059007, 059011, 083682, 083686
• CPC Class Codes: B21J 15/50 Removing or cutting devices for rivets

Abstract

A rivet removal tool for removing semi-tubular rivets from a workpiece. The tool has a punch head whose hemispherical tip bottoms within the rivet cavity to provide alignment therewith, and a shoulder whose edge shears the enlarged end of the aligned rivet.

Claims

1. A combined tool and tool holder for removing a semi-tubular rivet from a workpiece;

said tool comprising;

a solid metal shank of generally cylindrical shape having a first end adapted to be affixed in said tool holder and a second end having a punch head integrally extending therefrom;

said shank having a diameter adjacent said punch head substantially equal to but not exceeding the outer diameter of a rivet to be removed by said tool;

said punch head being of a cylindrical shape coaxial with said shank, and having a diameter smaller than the inner diameter of said rivet;

said tool having a shoulder with a shearing edge formed at the juncture of said shank and said punch head;

said punch head having a hemispherical surface at the tip thereof, and having a length sufficient to engage the bottom of the cavity in said semi-tubular rivet prior to the engaging of said shearing edge of said tool with said rivet

said tool holder comprising;

a metallic cylinder of generally cylindrical shape having a first end and a second end;

said first end of said tool holder having a flattened area on the surface thereof for retaining said tool holder in a punch press ram;

said second end of said tool holder being chamfered, having a cavity in the longitudinal axis thereof to accept said first end of said tool, and having a set screw therein for retaining said tool in said cavity.

2. A method for removing a rivet from a workpiece, said rivet being of the type having a tubular end defining a cylindrical cavity extending part way through the body thereof, the wall of said tubular end being expanded where it protrudes from the surface of said workpiece to clamp parts of said workpiece, said method using a tool having a punch head being of cylindrical shape and having a hemispherical tip, said punch head having an axial length at least equal to the depth of said cavity, said tool having a cylindrical shank coaxial with said punch head and of a larger diameter than said punch head forming a shoulder with a shearing edge, said method comprising the steps of:

inserting said punch head of said tool into said cavity with sufficient initial force to cause said punch head to bottom in said cavity and bring said rivet and said tool into axial alignment;

applying a sufficient intermediate axial force to said tool to cause said shearing edge to contact and shear the expanded wall of said tubular end of said rivet; and

applying a sufficient final axial force to said tool to cause said body of said rivet to be ejected from said workpiece.

3. An assembly comprising:

workpiece means having bore means of substantially uniform diameter;

a rivet of the type having a preformed head, a generally cylindrical body and tubular end extending only part way through said body of said rivet to form a cylindrical cavity having a conically-shaped bottom surface in said rivet;

said rivet being positioned within said bore means and having said tubular end thereof expanded where it protrudes above said bore means of said workpiece to retain said rivet in said workpiece; and

a tool for removing said rivet from said workpiece comprising;

a solid metal shank of generally cylindrical shape having a first end adapted to be affixed in a tool holder and a second end having a punch head integrally extending therefrom and engaging said tubular end of said rivet;

said shank having a diameter adjacent said punch head substantially equal to but not exceeding the outer diameter of said rivet to be removed by said tool;

said punch head being of cylindrical shape coaxial with said shank, and having a diameter smaller than the inner diameter of said rivet;

said tool having a shoulder with a shearing edge formed at the juncture of said shank and said punch head;

said punch head having a hemispherical surface at the tip thereof which engages said conically-shaped bottom surface of said cavity in said rivet prior to the engaging of said shearing edge of said tool with said rivet.