Method of machining screw
AssigneeNittan Valve Co., Ltd.
InventorsMichihiro Kameda, Masaaki Inoue
Life of this patent
Estimating the term…
Abstract
A method of machining a screw is provided that is capable of preventing formation of a protruding section at a thread tip section. A thread is formed by cutting on a cylindrical body, and a surface of the thread is plastically deformed by rolling. Because of the cutting, a width between-side surfaces of a thread tip section is in a narrowed state as compared to a normal width. This width is narrowed toward a tip of the thread while a thread body section has a width expanded as compared to a normal width. Consequently, the side surfaces are formed to bulge by an excess thickness portion as compared to normal side surfaces. The rolling plastically deforms both side surfaces to cause the excess thickness portion to plastically flow toward the side surfaces.
Claims7
A method of machining a screw including forming a thread on a work material by cutting and subsequently plastically deforming a surface of the thread by rolling,
- wherein because of the cutting, a width between both side surfaces of a tip section of the thread is in a narrowed state as compared to a width between both normal side surfaces of the thread tip section and is gradually narrowed toward a tip of the thread while a body section closer to a base end as compared to the tip section of the thread has a width between both side surfaces of the thread body section expanded as compared to a width between both normal side surfaces of the thread body section so that each of the side surfaces of the thread body section is formed to bulge by an excess thickness portion as compared to the normal side surfaces of the thread body section, and
- wherein the rolling plastically deforms the both side surfaces of the thread body section to cause the excess thickness portion to plastically flow on the both side surfaces of the thread tip section such that the width of the tip section increases to normal and the thickness of the thread body section decreases to normal.
Dependencies are inferred from the claim text.