Method and structure for locknut with substantially rigid locking member

A method for locking a nut onto a bolt, comprising the steps of:

• (a) forming a locknut body with a top surface and a bolt-receiving void defined about a central axis having upper and lower ends;
• (b) forging an aperture at the locknut void upper top end, the aperture defined by an array of forged splines, each spline having first and second spline walls intersecting at an engagement edge, the engagement edges disposed about the central axis on an engagement edge diameter, a plurality of spline voids further defined between a first sidewall of one of the splines and a second sidewall of an adjacent spline;
• (c) internally threading the locknut void lower end with a plurality of internal threads having a common thread diameter defined from the central axis along and less than the spline engagement edge diameter, the threads further disposed along a thread body length dimension about equal to the thread diameter;
• (d) hardening the locknut to a first hardness;
• (e) forming a locking member with a cylindrical outer surface defined along an outer surface diameter larger than the spline engagement edge diameter, and a top work-piece engagement region;
• (f) hardening the locking member to a second hardness;
• (g) forcibly inserting the locking member into said aperture;
• (h) responsive to said insertion, the spline engagement edges impinging the locking member outer surface;
• (i) the spline engagement edges forming spline engagement regions on the locking member outer surface responsive to said impingement;
• (j) the spline engagement region and spline edges and walls cooperatively interfacing to retain the locking member within the aperture;
• (k) threading the locknut threaded body length onto a work-piece bolt having a third hardness and a plurality of common threads corresponding to the locknut threads until the locking member top work-piece engagement region compressively engages a work-piece surface;
• (l) further tightening the locknut about the bolt, thereby compressing the locking member between the splines and the work-piece engagement surface and bolt threads;
• (m) the locking member outer surface deforming and cold-flowing about the splines and into the spline voids responsive to said compressive force sufficient to remain engaged by the splines and rotate with the locknut if the locknut is subsequently loosened about the work-piece bolt;
• and
• (n) one of the member thread engagement region and the work-piece bolt threads deforming responsive to said compressive force and thereby locking the locknut into a fixed position relative to the work-piece threads.