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:
Sep. 20, 1994
Filed:
Mar. 08, 1993
Kurt Fischer, Schaffhausen, CH;
Hans Leutwiler, Schaffhausen, CH;
Georg Fischer AG, Schaffhausen, CH;
Abstract
The invention relates to a process for the compression of molding sand in casting molds having a pattern plate with a pattern arranged therein. The molding sand is introduced loosely into the molding space located above the pattern plate and is thereafter fluidized to a final pressure of 20 bar maximum by means of a compressed-air surge acting on the molding sand followed by compression, by mechanical pressing. The process of the present invention provides a smooth pressure surge which is subdivided into at least a two part gradient in its pressure-rise time curve, so that the first part of the pressure-rise gradient takes place from 0.3 to 18 bar/sec to a pressure P.sub.1 and the second part has an increased pressure-rise gradient which takes place from 18 to 95 bar/sec. to a pressure P.sub.2 where P.sub.1 <P.sub.2 .ltoreq.20 bar. Subsequently, the P.sub.2 pressure is reduced in an essentially controlled manner, with a pressure-reduction gradient of a minimum of 3 bar/sec., and the pressing operation is initiated during the controlled pressure reduction.