Rack bar and method for production thereof
AssigneeKondo Seiko Co., Ltd.
InventorKeiji TANABE
Life of this patent
Estimating the term…
Abstract
Disclosed herein are a rack bar and a method for production thereof. The rack bar is composed of a steel pipe (10) and an embedded metal core (14) placed therein. The steel pipe has rack teeth formed thereon by forging. The embedded metal core (14) is made of a metal softer than the steel pipe (10) and has its surface wave-shaped such that the bottom (20) is wide and the top (22) is narrow.
Claims9
A rack bar comprising a steel pipe with rack teeth and a bore, and a metal core which is embedded in the bore of the steel pipe, wherein the rack teeth are formed by forging the steel pipe, wherein the metal core is made of a metal softer than the steel pipe, wherein the metal core has a section with a surface which is wave-shaped in longitudinal cross-section with alternating peaks and troughs, each peak presenting a top surface and each trough presenting a bottom surface, and wherein the bottom surface is wider than the top surface.
(canceled)
A method for producing a rack bar, the method comprising the steps of:
- heating a rack tooth forming part of a steel pipe with a bore up to a temperature of 700° C. to 800° C. by high-frequency heating;
- placing a metal core made of a metal softer than the steel pipe in the bore of the steel pipe along the rack tooth forming part during the heating or immediately after the heating;
- forming rack teeth on the rack tooth forming part of the steel pipe by hot forging in such a way that the metal core made of a metal softer than the steel pipe is embedded in the steel pipe, and
- forming a wave-shaped surface, with alternating peaks and troughs, on a longitudinal section of the metal core during the hot forging, each peak presenting a top surface and each trough presenting a bottom surface, and wherein the bottom surface is wider than the top surface.
(canceled)
Dependencies are inferred from the claim text.