Patent ID: 6516650
Filing Date: 2003-02-11
Classification: B21H

Abstract:
A thread rolling die for producing a dog point thread by plastic deforming an outer surface of a screw blank where the dog point thread has a thread portion provided with external threads and a dog point having an outer diameter smaller than an outer diameter of the thread portion, comprising,a thread portion rolling surface having a thread portion die ridge for forming a groove of the thread portion of the dog point thread and a thread portion die groove for forming a ridge of the thread portion of the dog point thread; and a dog point rolling surface provided in parallel with the thread rolling surface and having a dog point die ridge for forming a groove of the dog point of the dog point thread and a dog point die groove for forming a ridge of the dog point of the dog point thread; wherein a crest of the dog point die ridge is positioned higher than a crest of the thread portion die ridge, and a root of the dog point die groove is positioned lower than a root of the crest of the thread portion die ridge, and a distance between the crest and root of the dog point die ridge is smaller than a distance between the crest and root of the thread portion die ridge.