Norman M Dahl Deceased1100 Polaris Dr, Newport Beach, CA 92660

4035858, Jul 19, 1977

Mar 8, 1976

5/664574

Norman C. Dahl - Lexington MA

B21K 144

10 27H

A method for manufacturing bolts of a given grade and size in which, after forming, threading and heat treating, each bolt is work hardened by the application and subsequent removal of a tensile force of magnitude somewhat above the minimum proof load for the given grade and size of bolt, so that all bolts so treated will have the same yield point and the torque rotation curve for each bolt will have a discontinuity in slope at this common yield point.

4348141, Sep 7, 1982

Nov 19, 1979

6/095166

Norman C. Dahl - Lexington MA

F16B 3500
F16B 3102

411389

A metal fastener having a well-defined yield point and improved elongation beyond the yield point and a tensile strength (force) at least as large as the specified minimum for the grade, size, and threads of said metal fastener, the metal fastener of nominal diameter D, which metal fastener comprises in combination: an externally threaded component having threads of nominal diameter D; a circular, cylindrical shank component having a diameter D. sub. S equal to or substantially equal to said nominal diameter D extending axially to one end of the threaded component; and a head component for the application of torque to the fastener extending axially to the other end of the shank component; the fastener being characterized by an axially extending hollow cavity positioned therein within the shank component, and not extending substantially into the threaded component, the maximum cross-sectional area of the hollow cavity in the shank component being greater than the minimum cross-sectional area within any part of the hollow cavity which extends into the head or threaded components.

4142266, Mar 6, 1979

Jul 18, 1977

5/816265

Norman C. Dahl - Lexington MA

F16B 3102

10 27R

An improved method for creating built-in overload protection against further yielding in a bolt which previously has been tightened to its yield point, the method comprising rotating the bolt head or nut in the direction opposite from tightening while measuring the wrenching torque required for this rotation and stopping the rotation when the magnitude of the wrenching torque indicates that the torque acting in the bolt shank is fifty percent or less of the value existing at the end of tightening; and, a pulsed air motor wrench which at the end of tightening a bolt to its yield point automatically shifts to an untightening mode of operation and stops untightening when the untightening wrenching torque becomes equal to or exceeds the value CT. sub. WY wherein C is a numerical constant determined theoretically or experimentally and T. sub. WY is the wrenching torque acting at the end of tighening.

4037282, Jul 26, 1977

Jun 7, 1976

5/693546

Norman C. Dahl - Lexington MA

F16B 3102

10 27R

A method for creating built-in overload protection against further yielding in a threaded bolt which previously has been tightened to its yield point, said method comprising: reducing the torque acting in the shank of said bolt to fifty percent or less of the value existing at the end of tightening, said reduction in torque being accomplished by rotating the bolt head or the nut in the direction opposite from tightening through an angle. theta. such that the reduction in twist of said shank causes said torque to reduce to fifty percent or less of the value existing at the end of tightening and where said angle of rotation. theta. is not large enough to cause decrease in the tension existing in said bolt at the end of tightening.

4338054, Jul 6, 1982

Nov 19, 1979

6/095165

Norman C. Dahl - Lexington MA

F16B 3500

411424

A metal fastener characterized by a sharp yield point and improved elongation beyond the yield point and a tensile strength (force) at least as large as the specified minimum for the grade, size, and threads of said metal fastener, which metal fastener has a nominal diameter D and comprises: one or more externally threaded components having threads of nominal diameter D with a stress area A. sub. s ; a nonthreaded shank component having a diameter D. sub. s equal to or substantially equal to the nominal diameter D extending axially with the threaded components; the shank component characterized by a reduced portion of axial length L. sub. r, the reduced portion having an axially transverse cross-sectional area A. sub. r sufficiently less than the stress area A. sub. s of the threaded components along substantially the axial length L. sub.

4078273, Mar 14, 1978

May 5, 1977

5/794302

Norman C. Dahl - Lexington MA

B21K 144

10 27H

A method for manufacturing bolts of a given grade and size in which, after forming, threading and heat treating, each bolt is work hardened by the application and subsequent removal of a tensile force of magnitude somewhat above the minimum proof load for the given grade and size of bolt, so that all bolts so treated will have the same yield point and the torque rotation curve for each bolt will have a discontinuity in slope at this common yield point.