Patent FR-2985925-A1 (FR)
Title: Shell, useful for manufacturing bladed elements of turboshaft engine of aircraft by lost-wax casting, comprises thermal isolation coating carried out using set of thermal isolation strips for recovering part of external surface of shell
Inventor: GUERCHE DIDIER
IPC: B22C9/04
Filed: 2012-01-24
Abstract: The shell comprises a set of bladed shell elements (1b) for obtaining bladed elements of a turboshaft engine, a metal distributor (12b) having a central axis (14b), a set of metal casting arms (20b) distributed about the central axis of the distributor, where each of the casting arm includes a first end connected to the distributor, and a thermal isolation coating carried out using a set of thermal isolation strips for recovering a part of an external surface of the shell. The thermal insulation strips surrounds each of the bladed shell elements along a radial portion of the shell elements. The shell comprises a set of bladed shell elements (1b) for obtaining bladed elements of a turboshaft engine, a metal distributor (12b) having a central axis (14b), a set of metal casting arms (20b) distributed about the central axis of the distributor, where each of the casting arm includes a first end connected to the distributor, and a thermal isolation coating carried out using a set of thermal isolation strips for recovering a part of an external surface of the shell. The thermal insulation strips surround each of the bladed shell elements along a radial portion of the bladed shell elements and surround the shell. The coating presents a thermal gradient of resistance according to a radial direction of the bladed shell elements. The strips have same thermal resistance. Each bladed shell element comprises a blade portion (2b) between a first end portion defining a footprint of a platform and a second end portion delimiting a cavity of the platform. The second end of each casting arm is connected to the first end portion of one of the bladed shell elements. The second end portion is offset from the first end portion in the direction of the central axis of the distributor in the same direction as the offset of the second end of the arm relative to the casting at its first end. The blade portion includes a zone of trailing edge and a zone of leading edge opposite to the zone of trailing edge. Each bladed shell element includes a metal tank connected to the second end part so as to extend from the zone of leading edge in remote. The thermal isolation stripes comprises: a first strip associated with each bladed shell element and surrounding its associated bladed shell element over an entire length according to a radial direction of the bladed shell elements; a second strip that is associated with each bladed shell element, partially recovers the first strip, surrounds its associated element on the radial portion and includes the first end part and the blade portion; a third strip surrounding a periphery of the shell to cover the casting arms, the first end part and a higher radial portion of the blade portion; a fourth strip partially recovering the third strip and surrounding the periphery of the shell to cover only the casting arms; a fifth strip surrounding the periphery of the shell to cover only the bladed shell elements; a sixth strip surrounding the periphery of the shell and the third strip to cover the radial portion, including the first end part and a portion of the part blade and extending into an annular window; a seventh strip surrounding the periphery of the shell to cover surfaces with the tank radially directed towards outside and radial ends of the second end part; an eighth strip surrounding the periphery of the shell and partially recovering the seventh strip to cover surfaces with the tanks directed radially towards outside; and a ninth strip orthogonally laid out with the central axis on which the ninth strip is centered and from which the ninth strip extends radially until covering a circumferential end of the eighth strip. The second strip is placed in an annular space centered on the central and defined between the tank and the zone of trailing edges. The second strip is centered on the central axis to cover the first strip and to surround an outside of the radial portion of each bladed shell element, and includes only one portion of the blade portion extending from the second end part. The second and third strips having opposite ends define the annular window at which the shell has no band. An independent claim is included for a method for manufacturing bladed elements of a turboshaft engine of an aircraft.