Method for producing a turbine engine part, and resulting mould and intermediate blank

1. A method for producing at least one metal turbine engine part, comprising:

casting a metal alloy in a mould in order to produce a blank; and

machining the blank in order to produce the at least one part,

wherein the blank obtained by casting is an externally solid polyhedron having only eight external sides, including first, second, third, and fourth sides, the third and fourth sides extending between the first and second sides and flaring apart from the first side towards the second side, first at a first angle and subsequently, from a break of slope, at a second larger angle larger than the first angle, and said at least one part is machined in the blank.

2. The method according to claim 1 , wherein the blank is externally defined by first and second truncated pyramids, so that external sides of the blank are defined by said first and second truncated pyramids, the first and second truncated pyramids each having a larger base and a smaller base, each base having a surface, the surface of the larger base exceeding the surface of the smaller base, the second truncated pyramid being an extension of the first truncated pyramid on the larger base of the first pyramid which exactly overlaps the smaller base of the second truncated pyramid.

3. The method according to claim 1 , wherein:

said at least one part is a blade comprising a longitudinal axis and, along such axis, a root at a first end, a heel at a second end, and a curved section vane which extends there between and has a first convex side and a second concave side, and

fifth and sixth sides of the blank each have a general shape of a first and a second trapezoid that extend in the same plane, each of said trapezoids having a larger base and a smaller base each having a surface, the surface of the larger base exceeding the surface of the smaller base, and one of said trapezoids extending the other of said trapezoids on the larger base of the first trapezoid which is contiguous to the smaller base of the second trapezoid.

4. A moulded blank, wherein the moulded blank comprises an externally solid polyhedron having only eight external sides, including first, second, third, and fourth sides, said third and fourth sides extending between the first and second sides and flaring apart from the first side towards the second side, first at a first angle and subsequently, from a break of slope, at a second angle larger than the first angle.

5. The moulded blank according to claim 4 , wherein the third and fourth sides each have a generally trapezoidal shape.

6. The moulded blank according to claim 4 , wherein the moulded blank has a plane of symmetry perpendicular to the first and second sides which are mutually parallel.

7. The moulded blank according to claim 4 , wherein:

the first angle α ranges from 0° to 15°,

the second angle γ is smaller than 120°,

the third and fourth sides have a total flaring angle, between the first and second sides, which ranges from 1° to 15°, and

the break of slope is located at less than 85%, from the shortest distance between the first and second sides, starting from the first side.

8. The moulded blank according to claim 4 , wherein:

the moulded blank further comprises fifth and sixth sides,

the third and fourth sides each have a generally trapezoidal shape, and

the fifth and sixth sides each have a general shape of a first and a second trapezoid, each of said trapezoids having a larger base and a smaller base, each of said larger and smaller bases having a surface, the surface of the larger base exceeding the surface of the smaller base, and one of said trapezoids extending the other of said trapezoids, on the larger base of the first trapezoid which is contiguous to the smaller base of the second trapezoid.

9. A moulded blank, wherein the moulded blank is externally defined by first and second truncated pyramids, so that external sides of the blank are defined by said first and second truncated pyramids, each of said first and second truncated pyramids comprising a larger base and a smaller base, each of said larger and smaller bases having a surface, the surface of the larger base exceeding the surface of the smaller base, and the second truncated pyramid being an extension of the first truncated pyramid on the larger base of the first pyramid which exactly overlaps the smaller base of the second truncated pyramid,

wherein a length of the moulded blank is delimited by the smaller base of the first truncated pyramid and the larger base of the second truncated pyramid.

10. A mould for implementing a method for producing at least one metal turbine engine part, comprising:

casting a metal alloy in a mould in order to produce a blank; and

machining the blank in order to produce the at least one part,

wherein the blank obtained by casting is an externally solid polyhedron having only eight external sides, including first, second, third, and fourth sides, the third and fourth sides extending between the first and second sides and flaring apart from the first side towards the second side, first at a first angle and subsequently, from a break of slope, at a second larger angle larger than the first angle, and said at least one part is machined in the blank, the mould comprising at least one cavity for moulding therein a blank, the cavity comprising:

first and second sides located at the opposite one from the other and respectively defining a bottom and an opening for entering a metal alloy into the cavity, and

third and fourth sides, said third and fourth sides extending between the first and second sides and flaring apart from the second side towards the first side, first at a first angle and subsequently, from a break of slope, at a second angle larger than the first angle.

11. The mould according to claim 10 , wherein:

the first angle (α) ranges from 0° to 15°,

the second angle (γ) is smaller than 120°,

the third and fourth sides have a total flaring angle, between the first and second sides, which ranges from 1° to 15°,

and the break of slope is located at less than 85%, from the shortest distance between the first and second sides, starting from the first side.

12. A mould for implementing a method for producing at least one metal turbine engine part, comprising:

casting a metal alloy in a mould in order to produce a blank; and

machining the blank in order to produce the at least one part,

wherein the blank obtained by casting is a solid polyhedron having first, second, third, and fourth sides, the third and fourth sides extending between the first and second sides and flaring apart from the first side towards the second side, first at a first angle and subsequently, from a break of slope, at a second larger angle larger than the first angle, and said at least one part is machined in the blank, the mould comprising at least one cavity for moulding therein a blank externally defined by first and second truncated pyramids, so that external sides of the blank are defined by said first and second truncated pyramids, each of said first and second truncated pyramids having a larger base and a smaller base, each of said larger and smaller bases having a surface, the surface of the larger base exceeding the surface of the smaller base, and the second truncated pyramid being an extension of the first truncated pyramid on the larger base of the first truncated pyramid which exactly overlaps the smaller base of the second truncated pyramid, wherein a length of the moulded blank is delimited by the smaller base of the first truncated pyramid and the larger base of the second truncated pyramid.

13. A mould for implementing a method for producing at least one metal turbine engine part, comprising:

casting a metal alloy in a mould in order to produce a blank; and

machining the blank in order to produce the at least one part,

wherein the blank obtained by casting is an externally solid polyhedron having only eight external sides, including first, second, third, and fourth sides, the third and fourth sides extending between the first and second sides and flaring apart from the first side towards the second side, first at a first angle and subsequently, from a break of slope, at a second larger angle larger than the first angle, and said at least one part is machined in the blank,

the cavity has first, second, third, fourth, fifth and sixth sides,

the first and second sides are located at the opposite one from the other and respectively define a bottom and an opening for entering a metal alloy into the cavity,

the third and fourth sides extend between the first and second sides,

each of the third and fourth sides has a general trapezoidal shape, and,

the fifth and sixth sides each have a general shape of a first and a second trapezoid, each of said trapezoids having a larger base and a smaller base, each of said larger and smaller bases having a surface, the surface of the larger base exceeding the surface of the smaller base, and one of said trapezoids extending the other of said trapezoids on the larger base of the first trapezoid which is contiguous to the smaller base of the second trapezoid.

14. A method for producing at least one metal turbine engine part, comprising:

casting a metal alloy in a mould in order to produce a blank; and

machining the blank in order to produce the at least one part,

wherein the blank obtained by casting is an externally solid polyhedron having only eight external sides, including first, second, third, and fourth sides, the third and fourth sides extending between the first and second sides and flaring apart from the first side towards the second side, first at a first angle and subsequently, from a break of slope, at a second larger angle larger than the first angle, and said at least one part is machined in the blank, and wherein:

the third and fourth sides each have a generally trapezoidal shape, and

the solid polyhedron further comprises fifth and sixth sides, each having a general shape of a first and a second trapezoids, each of said trapezoids having a larger base and a smaller base, each of said larger and smaller base having a surface, the surface of the larger base exceeding the surface of the smaller base, and one of said two trapezoids extending the other of said two trapezoids on the larger base of the first trapezoid which is contiguous to the smaller base of the second trapezoid.