The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 11, 1999
Filed:
Mar. 16, 1998
Robert William Pugh, Sherwood Park, CA;
Stelco Inc., Ontario, CA;
Abstract
A process for heat treating a steel bar to produce a grinding rod having a softer core of at least 99% pearlite and having a hardness of less than 45 Rockwell C, an outer shell of martensite having a hardness of at least 50 Rockwell C and softer end portions having a hardness of less than 35 Rockwell C, where the softer end portions each having an engineered heat treated length less than 15 cm, comprises reheating a formed steel bar to above its austenitising temperature, transferring with minimal cooling the reheated bar to an open tubular quench vessel while securing the bar in the vessel to minimize bar warping in the vessel during quenching, introducing quench water into an inlet end of the vessel and passing the quench liquid along the vessel at high surface velocities exceeding 4 meters per second relative to bar surface to minimize thereby production of steam along the bar length and ensure uniform heat removal and removing quench water at an outlet end of the vessel, quenching the bar in the vessel for a period of time which provides a uniform annular layer for the hard outer shell of tempered martensite and the softer core of pearlite, and reheating each end portion of the bar in a furnace to elevate the end portion to above the austenitising temperature and air cooling each end portion to provide the engineered end portion hardness of less than 35 Rockwell C.