Design and Fabrication of Die Threading Machine

Abstract

A die cuts an external thread on cylindrical material, such as a rod, which creates a male threaded piece which functions like a bolt. Dies are generally made in two styles: solid and adjustable. Solid dies cut a nominal thread form and depth, whose accuracy is subject to the precision with which the die was made, as well as the effects of wear. Adjustable dies can be slightly compressed or expanded to provide some compensation for wear, or to achieve different classes of thread fit. The work piece (blank) to be threaded which is usually slightly smaller in diameter than the die's major diameter, is given a slight taper (chamfer) at the end that is to be threaded. This chamfer helps center the die on the blank and reduces the force required to start the thread cutting. Once the die has started it will self-feed. A periodic reversal of the die is often required to break the chip and prevent crowding. Die nuts, also known as rethreading  dies,  are  dies  made  for  cleaning  up  damaged threads, have no split for resizing and are made from a hexagonal bar so that a wrench may  be used to turn them. The process of repairing damaged threads is referred to as "chasing." Rethreading dies cannot be used to cut new threads.