Method and apparatus for making hex nuts from sheet metal

Claim 3

The method set forth in claim 1 wherein: subsequent blanks are consecutively processed in like manner to consecutively form the nuts by simultaneously performing said stamping, drawing, flattening, deburring, punching, and press forming steps on consecutively formed blanks.

Claim 4

Apparatus for forming sheet metal hex nuts of the type having a shoulder end and a flange end, with the nuts being for use as a clamp nut on electrical conduit connectors and coupling type fittings to secure a conduit end, extending through the nut throat, to the fitting body by having its shoulder cam a contractible gland, that is received in same through its flange end, against the fitting body to contract the gland against the conduit, said apparatus comprising: a progressive die forming structure including in consecutive order: a stamping station including means for consecutively stamping from a strip of sheet metal sheet metal blanks of polygonal side edge configuration having twice the number of sides the nut is to have, from a strip of sheet metal, a drawing station adjacent said stamping station including means for consecutively drawing the individual blanks to a cup shaped configuration defining a bottom wall at the nut shoulder end and a polygonally shaped upstanding side wall in circumambient relation about the bottom wall and terminating at the nut flange end in a marginal edge portion defined by the blank side edges, with the corners of the side wall being centered with the midpoints of alternate sides of the blank, and the exterior of the side wall defining the final external configuration and dimensioning of the nut, a press forming station adjacent said drawing station and including means for flattening the end of the blank marginal edge portion while countersinking the inner faces of said blank side wall from the nut flange end to adjacent the shoulder end thereof, a deburring station adjacent said press forming station and including means for deburring the outer edge of said blank side wall marginal edge, a punching station adjacent said deburring station and including means for punching the blank bottom wall to form the nut throat of predetermined size, and a countersinking station adjacent said punching station and including means for forming a substantially conical countersink about the inside margin of said blank throat that defines the gland engaging surface, said stations being arranged along a rectilinear feed path, and means for moving successive blanks between adjacent stations including: an elongate transfer member mounted for reciprocating movement along said feed path, said transfer member including gripper devices aligned with each of said stations adapted to releasably grip the blanks being processed at each station, means for reciprocating said transfer member longitudinally of said feed path in the timed sequence required to advance each blank held thereby one station prior to operation of the respective means at said stations and return said transfer member to its initial position during operation of the respective means to engage succeeding blanks for advancement to the next station, and means for intermittently feeding said sheet metal strip to said stamping station.

Claim 5

Apparatus for forming sheet metal hex nuts of the type having a shoulder end and a flange end, with the nuts being for use as a clamp nut on electrical conduit connectors and coupling type fittings to secure a conduit end, extending through the nut throat, to the fitting body by having its shoulder cam a contractible gland, that is received in same through its flange end, against the fitting body to contract the gland against the conduit, said apparatus comprising: a progressive die forming structure including in consecutive order: a stamping station including means for consecutively stamping from a strip of sheet metal sheet metal blanks of polygonal side edge configuration having twice the number of sides the nut is to have, from a strip of sheet metal, a drawing station adjacent said stamping station including means for consecutively drawing the individual blanks to a cup shaped configuration defining a bottom wall at the nut shoulder end and a polygonally shaped upstanding side wall in circumambient relation about the bottom wall and terminating at the nut flange end in a marginal edge portion defined by the blank side edges, with the corners of the side wall being centered with the midpoints of alternate sides of the blank, and the exterior of the side wall defining the final external configuration and dimensioning of the nut, a press forming station adjacent said drawing station and including means for flattening the end of the blank marginal edge portion while countersinking the inner faces of said blank side wall from the nut flange end to adjacent the shoulder end thereof, a deburring station adjacent said press forming station and including means for deburring the outer edge of said blank side wall marginal edge, a punching station adjacent said deburring station and including means for punching the blank bottom wall to form the nut throat of predetermined size, and a countersinking station adjacent said punching station and including means for forming a substantially conical countersink about the inside margin of said blank throat that defines the gland engaging surface, said stations being arranged along a rectilinear feed path, and means for moving successive blanks between adjacent stations including: an elongate transfer member mounted for reciprocating movement along said feed path, said transfer member including gripper devices aligned with each of said stations adapted to releasably grip the blanks being processed at each station, means for reciprocating said transfer member longitudinally of said feed path in the timed sequence required to advance each blank held thereby one station prior to operation of the respective means at said stations and return said transfer member to its initial position during operation of the respective means to engage succeeding blanks for advancement to the next station, and means for intermittently feeding said sheet metal strip to said stamping station.

Claim 6

The apparatus set forth in claim 3 including: means for tapping the countersunk surfaces of the blank side wall of the blank completed at said counter-sinking station.

Claim 7

The apparatus set forth in claim 4 wherein: said tapping means comprises a three fluted tapping tool.

Claim 8

The apparatus set forth in claim 4 wherein: said apparatus includes a tapping station aligned with said feed path and adjacent said countersinking station including means for press forming interrupted threads in the blank side wall countersunk surfaces, said tapping station comprising said tapping means.