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:
Oct. 12, 1993
Filed:
Mar. 11, 1991
Gerald P Backer, Southfield, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A method is disclosed for making an article, such as a cylinder head, having one or more hollow ceramic tubes, such as ceramic exhaust port liners, cast in-situ therein with reduced cracking or breakage of the ceramic tube from tensile and compressive stresses exerted on the ceramic tube during the casting process. The method involves forming a removable core in the ceramic tube of a core material having a thermal expansion coefficient not exceeding about 10 times that of the ceramic tube to minimize crack-causing differential thermal expansion-induced tensile stresses on the ceramic tube when molten metal is cast therearound, casting the molten metal about the cored ceramic tube in a mold cavity, stress relieving the cast article at an elevated temperature before the cast article cools to a lower temperature at which crack-causing differential thermal contraction-induced compressive stresses are exerted on the cast in-situ ceramic tube, and removing the core from the cast article.